What Is z/OS? The Operating System Running the World's Banks and ATMs

z/OS explained.

Right now, as you read this, someone somewhere is withdrawing cash from an ATM. A traveler is checking a flight status. A hospital is pulling up patient history. Various banks are processing millions of transactions at the same time in the background. All of that is handled by an operating system most people have never heard of: z/OS.

z/OS does not run on your laptop and it does not run in the cloud. It runs on a machine called a mainframe, and it quietly powers the most critical infrastructure on the planet. 95% of the world's ATM transactions, 87% of all credit card transactions, and over 30 billion transactions processed every single day are handled or supported by z/OS.

In this guide, we answer one question: what exactly is z/OS, and why does the world still depend on it in 2026?

What is an operating system?

In plain terms, an operating system is software that sits between the hardware and everything else. It manages memory, runs programs, controls storage, and makes sure everything works together. Windows, Linux, and macOS are all operating systems, and they're broadly designed for the same kind of workload: one user, or a handful of users, doing general-purpose computing on commodity hardware.

How is z/OS different from Windows or Linux?

z/OS was designed for IBM Z series mainframe computers, and it was not built for general-purpose computing. It was built for one very specific use case: running a high volume of transactions simultaneously, reliably, with zero downtime.

To put that in perspective: a single commodity Linux server might handle a few thousand transactions per second, or tens of thousands if it's well tuned. A well configured cloud cluster can push further. A single IBM Z mainframe running z/OS can process over 1 million transactions per second, on its own, while simultaneously running batch jobs in the background, managing terabytes of data, enforcing security policies, and producing audit logs for everything that happens.

That number matters when people say mainframes are outdated: 1 million transactions per second from a single machine, with 99.999% availability, meaning less than 5 minutes of downtime per year. The world's biggest banks haven't moved their core banking applications off this platform because of nostalgia. It's because nothing else does what z/OS does at that scale.

The history of z/OS

Understanding z/OS means understanding its history, and it's a genuinely remarkable story.

• 1964: IBM announces System/360, a family of computers designed to cover everything from small business to scientific research on a single compatible architecture. Before this, every computer was essentially on its own, software built for one machine did not run on another.
• OS/360 is built to run System/360, introducing concepts still in use today: jobs (units of work submitted to the system), batch processing (work that runs overnight and produces results by morning), and JCL, or Job Control Language.
• 1974: MVS (Multiple Virtual Storage) arrives, introducing virtual memory and making z/OS-style multitasking possible.
• 1980s: Further expansion massively increases how much memory the system can work with.
• 1990: IBM adds native Unix compatibility, a full Unix environment built directly into the platform.
• 1995: OS/390 arrives as a major refresh.
• 2001: IBM releases z/OS, named after the IBM Z hardware it runs on, bringing 64-bit addressing, improved scalability, and a tighter connection between software and hardware.

Today, z/OS continues to receive updates: container support, cloud integration, and AI workload capabilities. Every major bank running z/OS today has been building on this platform since the 1970s or 80s. Their core business logic, how accounts work, how transactions are checked, how risk is managed, is embedded in systems that have been running and improving for over 40 years. That's not legacy debt. That's decades of battle-tested engineering.

How z/OS actually works

z/OS is built around two types of work: batch processing and online transaction processing.

Batch processing happens in the background, usually overnight. Think about what a bank needs to do every night: calculate interest on millions of accounts, generate statements, reconcile transactions, run fraud detection across the day's activity. None of that needs to happen in real time, so it gets bundled into jobs, defined using JCL, submitted to the system, queued, executed, and reported on. The component that manages this is JES, the Job Entry Subsystem, the traffic controller for batch work.

Online transaction processing is completely different. When you tap your card at a shop, a transaction fires in milliseconds, hits the bank's system, and z/OS handles it through CICS, the Customer Information Control System. CICS manages thousands of concurrent requests in real time, looks up the account in DB2 (IBM's relational database), validates the transaction, updates the record, and returns a response, all in under a second.

Here's what makes z/OS extraordinary: both of these happen at the same time, on the same machine, on the same operating system, without either workload slowing the other down. That's possible because of the Workload Manager (WLM), which watches CPU, memory, and storage usage and allocates resources based on defined priorities, rebalancing thousands of times per second.

Underneath all of this is z/OS's memory model. Every program runs in its own isolated address space and cannot access another program's memory. If one application has a bug, even a serious one, it cannot bring down the rest of the system. This containment is a major reason z/OS achieves 99.999% availability, not because nothing ever goes wrong, but because when something does, the system contains it, recovers, and keeps working.

The hardware matters too. The IBM Z processor is a custom chip with dedicated circuits for cryptography, data compression, and transaction processing. The hardware and operating system are co-designed as a single system, which is part of why z/OS's performance can't simply be replicated on different hardware.

Key components of z/OS

• JES (Job Entry Subsystem): Makes batch processing possible. Receives submitted JCL jobs, assigns a job number, queues and schedules them, and captures the output (called SYSOUT) once complete.
• RACF (Resource Access Control Facility): Handles security. Every login, every read or write, every program execution, every command goes through RACF, which checks it against a database of users, groups, and permissions, and logs everything.
• DFSMS (Data Facility Storage Management Subsystem): Automatically manages data across hot, warm, and cold storage tiers, handling backup and recovery without requiring an army of storage administrators.
• CICS (Customer Information Control System): The middleware that makes online transaction processing possible, receiving requests, routing them to the right program, managing access to shared data, and returning a response.
• DB2 for z/OS: IBM's relational database, deeply integrated with CICS and RACF, scaled to transaction volumes that would be impossible on standard database systems.

z/OS vs Linux vs Windows

Factor	Windows	Linux (enterprise)	z/OS
Reliability	~99.9% (about 8 hours downtime/year)	~99.99% (about 50 minutes downtime/year)	99.999% (under 5 minutes downtime/year)
Scalability	Horizontal (add more servers)	Horizontal (add more servers)	Vertical (add processors/memory to one machine, no network latency between components)
Security	Strong	Strong	Centralized, auditable, fine-grained access control (RACF), decades of regulated-industry trust
Cost	Lower hardware/license cost	Lower hardware/license cost	Higher upfront cost, often lower total cost at scale once staffing, downtime, and risk are factored in

z/OS isn't trying to compete with Linux for web applications or developer tooling, and Linux isn't trying to process 1 million banking transactions per second on a single machine. They're different tools built for different jobs, and the world needs both.

Is z/OS still used in 2026? What about the cloud?

Yes, and increasingly the question isn't "cloud or mainframe," it's "mainframe and cloud." IBM has invested heavily in making z/OS a cloud-connected platform. Modern z/OS environments run Linux containers alongside mainframe workloads on the same hardware, expose mainframe data and services through REST APIs, and integrate with hybrid cloud platforms like IBM Cloud and Red Hat OpenShift.

The pattern in large enterprises: keep core transaction processing on z/OS, where it has always run, and use the cloud for everything around it, analytics, customer-facing applications, AI workloads, and development environments. The mainframe becomes the reliable core of a hybrid architecture, not a legacy system waiting to be replaced.

Are z/OS careers worth pursuing?

The mainframe skill shortage is real, and it's getting worse. The generation of engineers who built and maintain these systems is retiring, and the number of graduates entering the field is small, while demand for z/OS expertise isn't going anywhere, because the systems themselves aren't going anywhere.

Roles like z/OS system programmer, CICS developer, DB2 DBA, JCL developer, and mainframe security analyst consistently command higher salaries than equivalent roles in mainstream technologies, with significantly less competition for those roles. For developers looking for a differentiator in a market flooded with JavaScript and Python engineers, z/OS is one of the smartest skills to learn.

Summary: what is z/OS?

z/OS is an operating system that quietly runs the world. It processes more transactions every day than any other system on the planet. It achieves a level of reliability no other platform has matched, it has evolved continuously for over 50 years, and it isn't going anywhere. If you work in enterprise technology, or want to, understanding z/OS isn't optional. It's foundational.

Watch the full breakdown here: What is z/OS? The Operating System Running The World

CICS File Control: READ, WRITE, REWRITE, and DELETE

EXEC CICS READ UPDATE does not change a record. It retrieves the record and reserves it for a later REWRITE, DELETE, or UNLOCK. A program that treats UPDATE as a separate file command can hold a lock without completing the intended change.

CICS file control gives an application a command-level interface to VSAM and other supported files. The examples below use a KSDS named CUSTFILE and show the command sequence, response checks, and recovery points that matter in a COBOL transaction.

CICS file control commands read, add, change, and remove records while RESP, RESP2, and syncpoint handling protect the transaction.

CICS file control command map

Requirement	CICS command	Main point
Read one record	READ	Identify the record with RIDFLD; add UPDATE only when a change or delete will follow.
Add a record	WRITE	Pass the new record with FROM. A duplicate primary key normally returns DUPREC.
Change a record	READ UPDATE, then REWRITE	Keep the KSDS primary key unchanged and finish the update sequence promptly.
Remove a record	DELETE	Use a full key for a direct delete, or omit RIDFLD after READ UPDATE. ESDS records cannot be deleted.
Read sequentially	STARTBR, READNEXT, ENDBR	A browse must be started before the first READNEXT and ended when it is no longer needed.

If these commands are new to you, keep the CICS tutorial index open for related transaction topics. The VSAM data set selection guide explains when KSDS, ESDS, RRDS, and LDS organizations fit a workload.

Read a KSDS record by key

A direct READ identifies the record with RIDFLD. INTO names the application buffer. For a variable-length file, supply the correct length fields required by the file definition and installed CICS level.

       MOVE CUSTOMER-ID TO WS-CUSTOMER-KEY

       EXEC CICS READ
            FILE('CUSTFILE')
            INTO(CUSTOMER-RECORD)
            RIDFLD(WS-CUSTOMER-KEY)
            RESP(WS-RESP)
            RESP2(WS-RESP2)
       END-EXEC

       EVALUATE WS-RESP
          WHEN DFHRESP(NORMAL)
             CONTINUE
          WHEN DFHRESP(NOTFND)
             PERFORM CUSTOMER-NOT-FOUND
          WHEN OTHER
             PERFORM REPORT-FILE-ERROR
       END-EVALUATE

Use RESP and RESP2 together. RESP names the broad condition; RESP2 can identify the reason that applies to the command and resource definition. Record the file name, key in a safe display form, transaction ID, and both response values.

Write a new record

WRITE adds a record from the area named by FROM. For a KSDS, the record contains the primary key. A pre-read is usually unnecessary and introduces a race: another task can add the key between the read and the write. Issue the write and handle DUPREC.

       EXEC CICS WRITE
            FILE('CUSTFILE')
            FROM(CUSTOMER-RECORD)
            RESP(WS-RESP)
            RESP2(WS-RESP2)
       END-EXEC

       IF WS-RESP = DFHRESP(DUPREC)
          PERFORM CUSTOMER-ALREADY-EXISTS
       ELSE
          IF WS-RESP NOT = DFHRESP(NORMAL)
             PERFORM REPORT-FILE-ERROR
          END-IF
       END-IF

Other responses can include NOSPACE, NOTOPEN, NOTAUTH, IOERR, and LENGERR. The program should not translate all of them into "record not written"; operations staff need the actual condition.

Update with READ UPDATE and REWRITE

To change a record, retrieve it with the UPDATE option, modify the application buffer, and issue REWRITE. IBM documents TOKEN for associating a read-for-update with its later REWRITE, DELETE, or UNLOCK when a task has more than one outstanding update request.

       EXEC CICS READ
            FILE('CUSTFILE')
            INTO(CUSTOMER-RECORD)
            RIDFLD(WS-CUSTOMER-KEY)
            UPDATE
            RESP(WS-RESP)
            RESP2(WS-RESP2)
       END-EXEC

       IF WS-RESP = DFHRESP(NORMAL)
          MOVE WS-NEW-STATUS TO CUSTOMER-STATUS

          EXEC CICS REWRITE
               FILE('CUSTFILE')
               FROM(CUSTOMER-RECORD)
               RESP(WS-RESP)
               RESP2(WS-RESP2)
          END-EXEC
       END-IF

Do not leave a read-for-update outstanding. Complete it with REWRITE, DELETE, or UNLOCK. CICS also releases update state at a syncpoint, but using a syncpoint as routine cleanup hides a broken command sequence.

A KSDS primary key must not be altered during the rewrite. Fixed-length records must retain the defined length. Variable-length files require correct LENGTH handling and cannot exceed the maximum defined to VSAM.

Delete a record safely

CICS supports a direct keyed delete for a KSDS or RRDS. When business validation must occur first, read the record with UPDATE and then issue DELETE without RIDFLD. A record cannot be deleted from an ESDS.

       EXEC CICS READ
            FILE('CUSTFILE')
            INTO(CUSTOMER-RECORD)
            RIDFLD(WS-CUSTOMER-KEY)
            UPDATE
            RESP(WS-RESP)
            RESP2(WS-RESP2)
       END-EXEC

       IF WS-RESP = DFHRESP(NORMAL)
          AND CUSTOMER-STATUS = 'CLOSED'
          EXEC CICS DELETE
               FILE('CUSTFILE')
               RESP(WS-RESP)
               RESP2(WS-RESP2)
          END-EXEC
       ELSE
          IF WS-RESP = DFHRESP(NORMAL)
             EXEC CICS UNLOCK FILE('CUSTFILE') END-EXEC
          END-IF
       END-IF

A direct delete can name the full key in RIDFLD. When a non-unique alternate index is used, review IBM's documented DUPKEY behavior before assuming that every record with that alternate key was removed.

Browse records with STARTBR and READNEXT

READ NEXT is not the CICS syntax. A sequential browse uses STARTBR, one or more READNEXT or READPREV commands, and ENDBR. STARTBR positions the browse; it does not return the first record.

       EXEC CICS STARTBR
            FILE('CUSTFILE')
            RIDFLD(WS-CUSTOMER-KEY)
            RESP(WS-RESP)
            RESP2(WS-RESP2)
       END-EXEC

       PERFORM UNTIL WS-RESP = DFHRESP(ENDFILE)
          EXEC CICS READNEXT
               FILE('CUSTFILE')
               INTO(CUSTOMER-RECORD)
               RIDFLD(WS-CUSTOMER-KEY)
               RESP(WS-RESP)
               RESP2(WS-RESP2)
          END-EXEC

          IF WS-RESP = DFHRESP(NORMAL)
             PERFORM PROCESS-CUSTOMER
          END-IF
       END-PERFORM

       EXEC CICS ENDBR
            FILE('CUSTFILE')
       END-EXEC

Production code should distinguish ENDFILE from unexpected responses and should end an active browse on every exit path. Use REQID when one task needs multiple browses on the same file.

Record locking, recovery, and syncpoints

For a recoverable file, the unit of work determines whether changes are committed or backed out. A successful command is not the same as a durable commit. If the transaction later abends before syncpoint, CICS recovery can back out the file change.

• Keep the interval between READ UPDATE and REWRITE or DELETE short.
• Do not wait for terminal input, an HTTP call, or another slow service while holding an update lock.
• For RLS files, review NOSUSPEND, RECORDBUSY, and LOCKED behavior for the installed release.
• Use syncpoints according to the transaction's recovery design, not after every individual file command.

The broader CICS transactions guide explains how a transaction fits into online processing. File organization remains a VSAM concern; use the VSAM interview and operations reference for related record-access questions.

Common CICS file-control errors

Response	Typical meaning	Check
NOTFND	The requested record was not found.	Key value, key length, alternate path, and file contents.
DUPREC	A write attempted to add an existing key.	Business duplicate handling; do not retry the same write unchanged.
NOTOPEN	The file is not available in the required state.	CICS file resource status and associated VSAM data set.
LENGERR	The supplied or returned length is invalid for the file or buffer.	Fixed versus variable record definition, application buffer, and RESP2.
INVREQ	The option combination or file state is not valid for the request.	Command options, data set organization, browse state, and RESP2.

Production checklist

• Confirm the CICS file resource name, VSAM organization, key length, and record length.
• Handle expected conditions such as NOTFND, DUPREC, and ENDFILE separately from infrastructure failures.
• Capture RESP and RESP2 without exposing sensitive record data.
• End every browse and every read-for-update sequence on all branches.
• Test normal, missing-key, duplicate-key, file-closed, length-error, lock-contention, abend, and rollback paths.
• Verify that the transaction's syncpoint boundary matches the business unit of work.

Frequently asked questions

Is UPDATE a CICS file-control command?

No. UPDATE is an option on a read command. The program changes the returned data and then issues REWRITE.

Must DELETE always follow READ UPDATE?

No. A KSDS or RRDS record can be deleted directly with a full key. Use READ UPDATE first when the program must validate the current record or associate the delete with a token.

Can CICS delete an ESDS record?

No. IBM documents that ESDS records cannot be deleted. Choose another business technique, such as a logical status flag, when the design uses an ESDS.

What ends a CICS browse?

ENDBR explicitly ends the browse. A syncpoint or rollback can also end it, but the program should issue ENDBR when normal browse processing is complete.

IBM references

• IBM: Using CICS commands to update records
• IBM: Using CICS commands to delete records
• IBM: Sequential reading and browsing
• IBM: File-control response values

The safest update path is short and explicit: READ UPDATE, change the buffer, issue REWRITE, and inspect both response fields before the transaction reaches its syncpoint.

CICS Transactions: Understanding Transactions in the Mainframe.

CICS Transactions

In the ever-evolving world of technology, mainframes play a surprisingly enduring role. At the heart of many mainframe operations lies CICS (Customer Information Control System), a powerful transaction processing system created by IBM. Understanding CICS transactions is like unlocking a key to the mainframe's power. 

In this blog post, we'll dive deep into what CICS transactions are, why they matter, and how they underpin the robust capabilities of mainframe systems.

What is CICS?

Let's start with the basics. CICS is an online transaction processing (OLTP) system atop mainframe operating systems like z/OS. It serves as a bridge between user terminals and application programs, managing the flow of information and tasks quickly, securely, and reliably. CICS was designed to handle large volumes of transactions with exceptional efficiency - a vital component in industries like banking, finance, and retail.

The Heart of CICS: Transactions

So, what exactly is a CICS transaction? 

In simple terms, a transaction represents a unit of work, a series of related tasks executed as a single entity. CICS transactions are identified by a four-character transaction ID. For example, the transaction ID `DS01` could represent a transaction that displays a customer's account balance, or a banking transaction like withdrawing money from an ATM is a prime example.

The transaction involves the following steps or tasks:

• Checking the account balance.
• Verifying the PIN.
• Dispensing the cash.
• Updating the account balance.

All these steps must be completed successfully to ensure the transaction's integrity. That's where CICS comes in, coordinating the entire process. 

Characteristics of CICS Transactions

CICS transactions go beyond simple task execution. They possess a set of critical characteristics commonly known by the acronym ACID:

• Atomicity: A transaction either completes in its entirety or not at all. You won't get partial withdrawals from an ATM!
• Consistency: Transactions move data from one valid state to another, preserving data integrity.
• Isolation: Concurrent transactions operate independently, preventing interference and conflicts.
• Durability: The effects of a completed transaction are permanent. Once your cash is out, that change is logged for sure.

What Makes CICS Transactions Special?

CICS transactions are renowned for several things:

• Speed: Mainframes excel at high-throughput processing, and CICS is fine-tuned to handle enormous volumes of transactions.
• Reliability: Mission-critical systems demand fault tolerance. CICS transactions are designed to gracefully recover from failures.
• Scalability: As business needs grow, CICS can scale to manage increasing transaction loads.
• Security: Mainframes are highly secure, and CICS provides layers of protection for sensitive data.

The Role of CICS Transactions in Mainframe Transactions

Mainframe transactions often involve multiple steps - reading from a database, performing calculations, updating the database, etc. Each of these steps could be a separate CICS transaction.

CICS ensures that all transactions are processed reliably and in the correct order. If any part of a transaction fails, CICS can roll back all the changes made during that transaction, ensuring data integrity.

Use Cases for CICS Transactions

CICS transactions are at the core of countless business applications within organisations that rely on mainframes:

• Financial services: From real-time banking to stock trading, CICS helps move finances and executes critical trades.
• Insurance: Policy management, claims processing, and other core insurance operations can depend on CICS.
• Government: Tax systems, social welfare programs, and more often run with CICS's support.
• Retail: Inventory management, sales transactions, and the efficiency of supply chains frequently leverage the power of CICS transactions.

The Future of CICS Transactions:

Despite their long history, CICS transactions are no longer a relic of the past. CICS continues to evolve to meet the challenges of a modern IT landscape, seamlessly integrating with web services, cloud architectures, and big data. For mainframe systems, CICS remains a robust foundation for dependable transaction processing.

Conclusion.

Understanding CICS and its transaction approach is key to working effectively with mainframes. With its robust transaction handling, CICS remains an integral part of mainframe operations in various industries.

If this brief exploration of CICS transactions has piqued your interest, there's much more to discover. Consider further research on:

CICS: Empowering Modern Computing with Transaction Processing. 

CICS: How does a CICS Transaction work?

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CICS: Empowering Modern Computing with Transaction Processing. #cics

CICS - Customer Control System.

CICS (Customer Information Control System)

CICS (Customer Information Control System) is a transaction processing system that plays a crucial role in mainframe computing. It provides a robust and efficient environment for developing and executing online applications, enabling organizations to process large transactions with high performance and reliability. In this article, we will explore the significance of CICS in mainframe computing, its key features, benefits, use cases, and its support for modern application development.

Introduction to CICS (Customer Information Control System)

CICS is an IBM product that was first introduced in the 1960s and has evolved over the years to become a cornerstone of mainframe computing. It is designed to handle concurrent, interactive, and transaction-oriented applications, making it ideal for industries that require fast and reliable processing of business-critical data.

The Importance of CICS in Mainframe Computing

What is CICS?

CICS is a transaction processing system that provides a runtime environment for executing online applications on mainframe computers. It enables organizations to manage and control customer data, process transactions, and interact with various backend systems.

Role of CICS in Mainframe Computing

CICS is a middleware between the user interface and the backend systems, facilitating seamless communication and transaction processing. It ensures the integrity and consistency of data while providing high performance and reliability, making it an essential component of mainframe environments.

Key Features and Capabilities of CICS

CICS offers a wide range of features and capabilities, making it a powerful tool for transaction processing and application development.

Transaction Processing

CICS excels in handling high volumes of transactions efficiently. It provides features such as automatic transaction routing, transaction monitoring, and recovery mechanisms, ensuring that transactions are processed reliably and consistently.

Resource Management

CICS enables effective management of system resources, including databases, files, and program libraries. It provides resource pooling, caching, and sharing mechanisms, optimizing resource utilization and reducing overhead.

Security and Access Control

CICS incorporates robust security measures to protect sensitive data and ensure authorized access. It supports authentication, authorization, and encryption techniques, safeguarding against unauthorized transactions and data breaches.

Benefits of Using CICS in Mainframe Environments

Using CICS in mainframe environments brings several benefits that contribute to the overall efficiency and reliability of the system.

High Performance and Scalability

CICS is designed to handle high transaction volumes with minimal response time. It employs optimized algorithms and caching mechanisms to deliver exceptional performance and scalability, ensuring that applications can handle increasing workloads without compromising user experience.

Reliability and Availability

CICS ensures the continuous availability of applications and data, minimizing downtime and maximizing business continuity. It incorporates fault tolerance mechanisms, such as transaction logging and recovery, to maintain data integrity and recover from system failures quickly.

Integration with Legacy Systems

Many organizations rely on legacy systems to store and process critical data. CICS provides seamless integration with these systems, enabling modern applications to interact with and utilize existing resources effectively.

Use Cases of CICS

CICS finds applications in various industries where transaction processing and real-time data access are crucial.

Banking and Financial Services

In the banking and financial services sector, CICS is widely used for online banking, ATM processing, credit card transaction processing, and fraud detection. Its high performance, reliability, and security features make it an ideal choice for handling sensitive financial transactions.

Airlines and Travel Industry

CICS is utilized in the airline and travel industry for ticket reservations, flight schedules, baggage handling, and loyalty program management. It ensures smooth and efficient processing of transactions, contributing to a seamless customer experience.

Retail and E-commerce

In the retail and e-commerce sector, CICS enables real-time inventory management, order processing, payment processing, and customer support. Its scalability and reliability are crucial for handling the high transaction volumes typically encountered in these industries.

How CICS Supports Modern Application Development

CICS has evolved to meet the demands of modern application development and integration with emerging technologies.

Web Services and APIs

CICS supports the development and deployment of web services and APIs, allowing easy integration with other applications and systems. This enables organizations to expose mainframe functionality to modern web and mobile applications.

Support for Mobile Applications

With the proliferation of mobile devices, CICS provides features to develop and run mobile applications securely. It offers mobile-specific services, such as push notifications, offline data access, and device-specific authentication, enhancing the mobile user experience.

Integration with Cloud Technologies

CICS seamlessly integrates with cloud technologies, enabling organizations to leverage the scalability and flexibility of cloud environments. It allows the deployment of CICS applications on cloud platforms and facilitates communication between on-premises and cloud-based systems.

Future Trends and Innovations in CICS

CICS continues to evolve to meet the changing needs of modern computing environments. Here are some of the future trends and innovations in CICS.

Microservices Architecture

CICS is embracing the microservices architecture, enabling the development and deployment of lightweight, modular services. This architecture promotes agility, scalability, and easier integration with modern application development frameworks.

Containerization and DevOps

CICS is adopting containerization technologies, such as Docker and Kubernetes, to enhance portability and deployment flexibility. This allows organizations to leverage the benefits of containerization and adopt DevOps practices for faster and more efficient application delivery.

AI and Machine Learning Integration

CICS is exploring the integration of artificial intelligence (AI) and machine learning (ML) capabilities. This integration can enhance transaction processing, enable predictive analytics, and automate decision-making, further improving the efficiency and effectiveness of mainframe systems.

Conclusion

CICS (Customer Information Control System) plays a vital role in mainframe computing by providing a robust and efficient environment for transaction processing and online application development. With its high performance, reliability, and support for modern technologies, CICS continues to be a valuable asset for organizations across various industries. By embracing future trends and innovations, CICS remains a cornerstone of mainframe computing, ensuring seamless integration with emerging technologies and enabling businesses to thrive in the digital era.

FAQs

Q: Is CICS only applicable to mainframe computers?

A: Yes, CICS is specifically designed for mainframe computing environments.

Q: Can CICS handle high volumes of transactions?

A: Yes, CICS excels in processing high volumes of transactions efficiently.

Q: Does CICS support integration with legacy systems?

A: Yes, CICS seamlessly integrates with legacy systems, allowing organizations to leverage existing resources.

Q: Can CICS be deployed on cloud platforms?

A: Yes, CICS supports deployment on cloud platforms and facilitates communication between on-premises and cloud-based systems.

Q: Is CICS suitable for mobile application development?

A: Yes, CICS provides features and services specifically designed for developing and running secure mobile applications.

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The Importance of Mainframe Skills: Unlocking the Power of COBOL, JCL, VSAM, CICS, DB2, CA7, and More.

Mainframe Skills

Introduction

In the ever-evolving landscape of technology, certain skills continue to remain relevant and in high demand. Among these, mainframe skills such as COBOL, JCL, VSAM, CICS, DB2, CA7, and others hold immense importance. Despite the emergence of newer technologies, mainframe systems continue to power critical applications across industries worldwide. This article explores the significance of mainframe skills and why mastering these technologies can lead to lucrative career opportunities.

Mainframe Skills Overview

Before delving into the specific skills, it is essential to understand the broader concept of mainframe computing. Mainframes are high-performance computers that process vast amounts of data and handle complex transactions. They have been the backbone of large-scale business applications for decades, ensuring reliability, security, and scalability.

The Significance of COBOL

The term COBOL stands for Common Business-Oriented Language. It's one of the robust programming languages, that is designed for business applications. Despite being introduced in the late 1950s, COBOL remains prevalent in legacy systems. Many critical business operations, including financial transactions, healthcare systems, and government databases, rely on COBOL. Proficiency in COBOL opens doors to maintaining and modernizing these mission-critical applications.

Mastering JCL for Mainframe Success

JCL (Job Control Language) is a scripting language used to control and manage batch processing on mainframe systems. It defines the sequence of jobs and their dependencies, allocating system resources and directing data flow. JCL expertise is crucial for ensuring the efficient execution of batch jobs, optimizing system resources, and maintaining job schedules.

Understanding VSAM and Its Importance

VSAM (Virtual Storage Access Method) is a data management system used on mainframe systems. It provides efficient access to large volumes of data, offering features like random and sequential access. VSAM skills are vital for managing large databases and optimizing data retrieval and storage, enabling organizations to handle substantial amounts of information effectively.

Harnessing the Power of CICS

The CICS stands for Customer Information Control System. It's an online transaction processing system used on IBM Mainframes. It enables the execution of online transactions, serving as a bridge between users and back-end systems. Proficiency in CICS allows developers to design and develop interactive and responsive applications, ensuring smooth user experiences in real-time environments.

Leveraging the Potential of DB2

DB2 is a widely used relational database management system (RDBMS) on mainframes. It offers robust features for data storage, retrieval, and manipulation, providing the foundation for critical business applications. Mastering DB2 allows professionals to design and manage complex databases, ensuring data integrity, security, and efficient data access.

Navigating CA7 for Efficient Job Scheduling

CA7 is a job scheduling software used in mainframe environments. It enables the automation and coordination of batch jobs, ensuring the smooth execution of critical business processes. Knowledge of CA7 facilitates efficient job scheduling, resource optimization, and error handling, enhancing overall system performance and productivity.

The Benefits of Mainframe Skills in Today's World

Despite the growing popularity of cloud computing and distributed systems, mainframe technology continues to play a vital role in various industries. Mainframe systems excel in handling high-volume transactions, providing robust security, and offering unparalleled reliability. Organizations rely on mainframes to process sensitive data, run complex calculations, and ensure uninterrupted business operations. Therefore, possessing mainframe skills opens up a plethora of benefits and opportunities for professionals.

Industry Demand for Mainframe Professionals

The demand for mainframe professionals remains steady in sectors such as banking, insurance, healthcare, government, and retail. Many organizations heavily invest in mainframe systems, as they recognize the value of these robust and secure platforms. Consequently, there is a consistent need for skilled mainframe experts who can maintain, modernize, and optimize existing systems.

Job Opportunities for Mainframe Experts

Professionals with mainframe skills have a wide range of job opportunities at their disposal. They can work as COBOL programmers, JCL specialists, DB2 administrators, CICS developers, system analysts, mainframe architects, and more. These roles often come with attractive compensation packages and provide stability due to the industry demand for mainframe expertise.

Future Prospects and Growth

Contrary to the misconception that mainframes are fading away, they continue to evolve and adapt to changing technological landscapes. Mainframe vendors consistently innovate, integrating new capabilities and technologies into their systems. As a result, professionals with mainframe skills can stay relevant by embracing emerging trends such as cloud integration, mobile computing, and advanced analytics.

Training and Learning Resources

For those aspiring to acquire or enhance their mainframe skills, numerous training programs and resources are available. IBM offers a range of mainframe-related certifications and training courses, equipping individuals with the knowledge and expertise needed to excel in the field. Online platforms, educational institutions, and professional communities also provide learning opportunities to master mainframe technologies.

Conclusion

Mainframe skills like COBOL, JCL, VSAM, CICS, DB2, CA7, and others continue to hold immense importance in today's technology landscape. These skills provide professionals with a competitive edge and open up a world of career opportunities. By embracing mainframe technologies, individuals can contribute to the efficient functioning of critical business applications and secure their positions in a dynamic and evolving industry.

FAQs

Q: Are mainframe skills still relevant in today's era of cloud computing?

A: Absolutely! Mainframe systems excel in handling high-volume transactions and ensuring robust security, making them indispensable in various industries.

Q: Which industries rely heavily on mainframe systems?

A: Sectors such as banking, insurance, healthcare, government, and retail heavily depend on mainframe systems to process critical business operations.

Q: What are the job prospects for professionals with mainframe skills?

A: Mainframe professionals have a wide range of job opportunities, including roles such as COBOL programmers, JCL specialists, DB2 administrators, and system analysts.

Q: Can mainframe skills help in future career growth?

A: Yes, mainframes continue to evolve and integrate new technologies, providing opportunities for professionals to stay relevant and embrace emerging trends.

Q: Where can I learn mainframe skills and enhance my knowledge?

A: You can check out our Mainframe Course on Udemy and Skillshare. Additionally, IBM offers certifications and training courses for mainframe technologies. 

Mainframe JCL Course

Check out our COBOL Complete Reference Course, which is available on Udemy and Tutorial Point. You can also check out our Youtube Channel for more such videos. 

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IBM-CICS Top 100 Question & Answers 2023 | IBM-CICS Interview Questions & Answers For Experienced & Fresher.

IBM-CICS Interview questions and answers

Q.	What are the two CICS Signon transactions?
A.	CESN and CSSN.
Q.	What is the difference between CESN and CSSN?
A.	CESN is the sign-on transaction with the External Security Manager such as RACF. ESM user id and the associated password must be provided for CESN transaction. On the other hand, CSSN is the sign on the transaction without ESM. The OPNAME and PASSWORD defined in the SNT must be provided for this transaction.
Q.	What is the latest version of CICS?
A.	CICS TS Version 5.5
Q.	What are the two types of direct access files supported by CICS?
A.	VSAM and BDAM.
Q.	What are the two types of TD0s
A.	Intrapartition TDO and Extrapartition TDQ.
Q.	What is the difference between an Intrapartition TDQ and Extrapartition TDO?
A.	Intrapartition TDO is read or wrote by the program(s) in the same CICS system while Extrapartition TDQ is used by the applications outside the CICS system also.
Q.	What are the two types of interfaces provided by CICS to application programs?
A.	Command level and Macro level.
Q.	What is the function of the CICS translator?
A.	The CICS translator converts the EXEC CICS commands into call statements for a specific programming language. There are CICS translators for Assembler, PUI and COBOL.
Q.	What does 'pseudo conversational' mean?
A.	The programming methodology in which the task will not wait for the terminal user's response, but frees the resources after sending the message is called a pseudo-conversational technique. Terminating the task every time the application needs a response from the user and then starting the next transaction when the user presses any attention key is pseudo conversational processing.
Q.

IBM-CICS TOP 150 Interview Question and Answers 2019 | Best IBM-CICS Interview Questions for free.

CICS TOP 150 Interview Question and Answers.

These CICS Interview Questions have been designed particularly to get you familiar with the nature of questions you may encounter during your interview for IT Job.

Q.1   What happens to resources supplied to a transaction when an XCTL command is executed?

A        With an XCTL, the working storage and procedure division of the program issuing XCTL are released. The I/O areas, the GETMAIN areas and the chained Linkage Section areas (Commarea from a higher level) remain. All existing locks and queues also remain in effect. With a LINK, however program storage is also saved, since the transaction expects to return and use it again.

Q.2      What CICS command do you need to obtain the user logon-id?

A          You must code EXEC CICS ASSIGN with OPERID option.

Q.3      What is a resident program?

A         A program or map loaded into the CICS nucleus so that it is kept permanently in main storage and not deleted when CICS goes "short on storage."

Q.4      What is some of the information available in the EIB area?

A          The cursor position in the map are :

·                  Transaction id

·                  Terminal id

·                  Task number

·                  Length of the communication area

·                  Current date and time

·                  Attention identifier

Q.5      What information can be obtained from the EIBRCODE?

A     The EIBRCODE tells the application program if the last CICS command was executed successfully and if not, why not.

Q.6      What is the effect of including the TRANSID in the EXEC CICS RETURN command?

A          Next time the end user presses an attention key, CICS will start the transaction specified in the TRANSID option.

Q.7      What is the function of the EXEC CICS HANDLE CONDITION command?

A       To specify the paragraph or program label to which control is to be passed if the "handled condition" occurs.

Q.8      How many conditions can you include in a single HANDLE CONDITION command?

A          No more than 16 in a single handle condition. If you need more, then you must code another HANDLE CONDITION command.

Q.9      What is the EXEC CICS HANDLE ABEND?

A       It allows the establishing of an exit so cleanup processing can be done in the event of abnormal task termination.

  

Q.10    What is the difference between an EXEC CICS HANDLE CONDITION and an EXEC CICS IGNORE command?

A          A HANDLE CONDITION command creates a "go-to” environment. An IGNORE command does not create a go-to environment; instead it gives control back to the next sequential instruction following the command causing condition. They are opposites.

Q.11    What happens when a CICS command contains the NOHANDLE option?

A          No action is going to be taken for any exceptional condition occurring during the execution of this command.  The abnormal condition that occurred will be ignored even if an EXEC CICS HANDLE condition exists.  It has the same effect as EXEC CICS IGNORE condition except that it will not cancel the previous HANDLE CONDITION for any other command.

Q.12    What happens when a CICS command contains the RESP option?

A.         No action is going to be taken for any exceptional condition occurring during the execution of this command. When an abnormal condition occurs, the CICS response code is a field in the program work area and can be checked later (usually at the next sequential instruction).

Q.13    Suppose that an application program uses the HANDLE AID ENTER (main-logic) and the HANDLE CONDITION ERROR(abort-rtn) command. If the program issued a RECEIVE MAP and a MAPFAIL condition occurred, which process will take control : main-logic or abort-rtn?

A          Main-logic will receive control because Handle Aid has priority over Handle Condition.

Q.13    When the task suspends all handle conditions via. the PUSH command, how does the task re-activate all the handle conditions?

A          By coding an EXEC CICS POP HANDLE command.

Q.14    What is the difference between the INTO and the SET option in EXEC CICS RECEIVE MAP commands?

A          The INTO option moves information in the TIOA into the reserved specified area, while the SET option simply returns the address of TIOA to the specified BLL cell or "address-of" a linkage section.

Q.15    Define the function of Basic Mapping System (BMS).

A          BMS allows the application to be device-independent. It translates the formatted data stream, thus enabling the application to reference data by symbolic labels.

Q.16    Suppose you have a field in a map named ACCTID and you want it bright. Explain how can you do this during the execution of application?

A          By moving either DHFBMBRY to the ACCTIDA field in symbolic map (bright only) or DFHBMASB to the ACCTIDA field in the symbolic map (askip bright).

Q.17    What are the three ways available for a program to position the cursor on the screen ?

A          1. Static positioning. Code the insert cursor (IC) in the DHFMDF BMS macro.

2. Relative positioning. Code the CURSOR option with a value relative to zero (position 1,1 is zero).

3. Symbolic positioning. Move high values or -1 to the field length in the symbolic map (and code CURSOR on the SEND command).

Q.18    Reducing the data traffic is a very important factor in an on-line environment. Explain the difference between the MAPONLY and DATAONLY options in the EXEC CICS SEND MAP.

A          A vast majority of the maps are defined as input/output. Therefore, to reduce data transmission first time a map is sent, you should use MAPONLY because this will set up the initial template on screen. After that the application needs to be sent only variable data in the symbolic map (DATAONLY).

Q.19    What is the Modified Data Tag (MDT)?

A          The MDT is a 1-bit attribute character of a BMS field. When it is set on, CICS will transmit the data contained in the associated map field.

Q.20    Name three ways the Modified Data Tag can be set on?

A:         The Modified Data Tag can be set on :

1. When the user enters data into the field

2. When the application program moves the DFHBMSFSE to the attribute character

3. By defining it in the BMS macro definition

Q.21    How do you specify in your program which fields are not to be sent to a map (terminal)?

A          By filling the fields with low values.

Q.22    What happens if neither MAPONLY nor DATAONLY are specified?

A          The data from the physical map and the data from the symbolic map are merged, causing an increase in the data transmission.

Q.23    What is a mapset?

A          A mapset is a collection of BMS maps link-edited together.

Q.24    What is the function of the DFHMDF BMS macro?

A          The DFHMBF macro defines fields, literal and characteristics of a field.

Q.25    The DFHMDF is a subset (a subdivision) of which BMS macro?

A          DFHMDF is a BMS macro that is a part of the DHFMDI macro.

Q.26    What is the function of Terminal Control Table (TCT)?

A          The TCT defines the characteristics of each terminal with which CICS can communicate.

Q.27    When an application program issues an EXEC CICS RECEIVE MAP command and there is no data sent back to the application program, what exceptional condition will occur?

A          A MAPFAIL condition will occur.

Q.28    What does it mean when EIBCALEN is equal to zeros?

A          When the length of communication area (EIBCALEN) is equal to zeros, it means that no data was passed to the application.

Q.30    Which CICS system program is responsible for handling automatic task initialization?

A:         The Transient Data Program(TDP).

Q.31    What are the differences between a Temporary Storage Queue (TSQ) and Transient Data Queue (TDQ)?

A         The differences between a Temporary Storage Queue (TSQ) and Transient Data Queue (TDQ) are :

·                  Temporary Storage Queue name are dynamically defined in the application program, while Temporary Data Queues must first be defined in the DCT (Destination Control Table).

·                  When a TDQ contains a certain amount of records (trigger level), a CICS transaction can be started automatically. This does not happen when using a TSQ.

·                  TDQ (extrapartition) may be used by batch by batch application; TSQ cannot be accessed in-batch. The Transient Data Queue is actually a QSAM file.

·                  You may update an existing item in a TSQ. A record in a TDQ cannot be updated.

·                  Records in TSQ can be read randomly. The TDQ can be read only sequentially.

·                  Records in Temporary Storage can be read more than once, while records stored in Temporary Data Queues cannot. With TDQs it is “one read” only.

Q.32   What will happen if a task issues an EXEC CICS DELETEQ TD against an Extrapartition Transient Data Queue?

A       An invalid request exceptional condition will occur. The default action is that the task will be terminated.

Q.33   In an in-line environment, how can you prevent more than one user from accessing the same Transient Data Queue at the same time?

A       By issuing an EXEC CICS ENQ against the resource. When processing is completed a DEQ should be executed.

 Q.34  What are the eight steps for a CICS program development?

Get the complete specification

Get related sourcebooks and subprograms

Design the program

Update the CICS Tables

Code and compile the map definition

Code the program

Compile the program

Test the program.  

Q.35 What is a PPT and how it is used?

A PPT contains a valid list of program names and it also indicates the storage address if the program has already been loaded.  CICS uses PPT to determine whether it will load a new copy of the program if the program is invoked.

Q.36  Have you ever heard of SNT in CICS Processing?

          Yes, it contains the names of all valid users of the system.

Q.37    What is the use of DFHCOMMAREA and where it is located?

            It helps to transfer data between two transactions and it is located in the LINKAGE 

            SECTION.

Q.38    Are you familiar with CEMT and CSMT functions?  What do these transactions do 

            for  you?

            These are normally supervisory functions, where they can be used to cancel tasks running 

            at a different terminal.  CSMT is used to update PPT.  But I never had much chance to 

            use them.

Q.39  What transaction will you use to debug a CICS Program?

            CEDF, which means CICS Execution Diagnostic facility.

Q.40    What XCTL and LINK command is used for?

            XCTL command transfers control to another program without setting up a return mechanism 

            whereas the LINK command transfers control to next logical lower level with a return 

            mechanism

Q.41    Why the EXEC CICS HANDLE command is used?

It is used to specify what action the program needs to take when certain exceptional conditions occur.

Q.44    Is there any way of releasing a resource previously enqueued by a task other than by issuing an EXEC CICS DEQ command?

A:      You can issue a SYNCPOINT command.  You can also RETURN control to CICS, as CICS automatically release a resource when a task is terminated.

Q.45    When an application is invoked via. the EXEC CICS START command with the FROM option, how does the application gain access to the common area?

A          An EXEC CICS RETRIEVE command will access the common area.

Q.46    What happens when an EXEC CICS SYNCPOINT is issued?

A          The Logical Unit of Work (LUW) is terminated. Everything on the Deferred Work Element (DWE) chain is cleaned up. If Dynamic Transaction Backout (DTB) is on, everything is committed. GETMAIN areas are freed. File locks are released. I/O areas and linkage sections are released.  Browses are terminated. Working storage is not affected.

Q.47    What is a Logical Unit of Work?

A:         A Logical Unit of Work is all the processing that takes place between two "sync points."

Q.48    The DFHCOMMAREA is used to pass information from one application to another.  What are some other ways that this  function can be accomplished?

A          You can also pass information in the following ways :

·                  By using a Temporary Storage Queue

·                  By using an intrapartition TDQ

·                  By using the Task Work Area

·                  By using TCTUA

·                  Through a file

Q.49    How do you define a Task Work Area?

A.         By defining it in on the PCT (the Program Control Table).

Q.50    What is stored in the Temporary Storage Table?

A          The TST contains the names of Temporary Storage Queues that are to be recovered in the event of an abend.

Q.51    What information do you get when an EXEC ASSIGN STARTCODE is issued?

A:         You will be able to determine if the application was started by :

·                  a transient data trigger level (QD)

·                  a START command (S,SD)

·                  user (U) or terminal input (TD)

·                  Distributed Program Link (D, DS)

Q.52    Which CICS command must be issued by the application in order to gain access to the Common Work Area (CWA)?

A          EXEC CICS ADDRESS with CWA option.

  

Q.53    In which CICS table would you specify the length of TASK WORK AREA (TWA)?

A          In the Program Control Table (PCT).

Q.54    Explain the function performed by the Program Control Table (PCT)?

A          The PCT defines relationship between a transaction and an application program.

Q.55    When a data table is loaded into memory using the EXEC LOAD command, how does the application program free that memory when the table is no longer needed?

A          By coding an EXEC CICS RELEASE command with the program option.

Q.56    What is the function of HOLD option in the EXEC CICS LOAD command?

A          When a program is loaded from the CICS DFHRPL concatenation library (into main storage), the HOLD option will result in the program remaining in memory after the task terminates.  When this option is not specified, main storage is automatically released by CICS.

Q.57    Explain the function of the File Control Program (FCP)?

A.         The FCP provides the application program with the ability to read, browse, add, delete, and update records in a file defined in the FCT.

Q.58    What is the function of File Control Table?

A          It defines the file and contains characteristics of the dataset.

Q.59    If an application has a VSAM/KSDS file READ command with the update option and it finds that the update is no longer required, how does the application release the exclusive control of the record read?

A          By executing an EXEC CICS UNLOCK command with the File or Dataset option. A SYNCPOINT will also release the exclusive control.

Q.60    What is a deadlock?

A          Deadlock (also known as a "deadly embrace") occurs when a task is waiting for a resource held by another task which in turn is waiting for a resource held by the first task.

Q.61    Which CICS program is responsible for the management of DSA (the Dynamic Storage Area)?

A          The storage Control Program (SCP).

Q.62    What happens when an application issues an EXEC CICS GETMAIN command to obtain main storage and SHARED option is specified?

A:         There is no automatic release of the obtained storage at the end of task which requested it.

Q.63    How can an application release main storage acquired by an EXEC CICS GETMAIN command?

A          By coding an EXEC CICS FREEMAIN command with the data. SYNCPOINT will also release the storage area.

Q.64    What is the function of the REQID in the EXEC CICS STARTBR command?

A          When you have multiple browse operations at the same time on the same file, the REQID must be coded on the READ Next/Prev command to distinguish one browse from the other.

Q.65    Which CICS command must the application program issue to terminate a browse?

A          An EXEC CICS ENDR command. SYNCPOINT also ends the browse.

Q.66    What is the function of the EXEC CICS RESETBR Command?

A          To reposition the browse (with VSAM files this can be done just by altering the RIDFLD) and to change the characteristics specified on the STARTBR command without ending the browse.

Q.67    When debugging a CICS application, why would you use the CEBR command?

A          To view the contents of the TSQ or TDQ.

Q.68    Mention some of the most common operations you can perform with the CEMT CICS transaction?

A          Create a new copy of an application program           CEMT S PR(prgname) NEW

Close a file from CICS                                                CEMT S DA(filename) CLO UNE

Disable a transaction                                                  CEMT S TRANS(transid) Dis

Q.69    What is the function of the CEDA transaction?

A          It is used to perform the Resource Definition on-line operation (RDO). It adds, deletes, and changes table entries.

Q.70    What CICS command does the application have to issue to update an existing record in a VSAM/KSDS file?

A          The EXEC CICS REWRITE command.

Q.71    What CICS command does the application have to issue to update an existing record in a TS queue?

A          The EXEC CICS WRITE command with the rewrite option and the item number.

Q.72    What is the purpose of CICS BIF DEEDIT?

A.         To remove all characters other than digits from an alphanumeric field. Remaining digits will be right-justified and padded with zeros as necessary.

Q.73    What is the Base Locator for Linkage (BLL) used for?

A          The BLL is used to address storage outside the working-storage section of the application program. A set of BLL cells is also known as the parameter list. It is not used (explicitly) in COBOI II, although the BLL cells can be found in the TGT of a COBOL II program.

Q.74    Explain the term "transaction routing".

A          Transaction routing is a CICS "mode" of intercommunication which allows a terminal connected to local CICS to execute another transaction owned by a remote CICS.

Q.75    Explain the term "function request shipping".

A          Function request shipping is one of the CICS modes of intercommunication which allows an application program in a local CICS to access resources owned by a remote CICS.

Q.76    Explain the term "MRO" (Multi-Region Operation)?

A:         MRO is the mechanism by which different CICS address spaces within the same CPU can communicate and share resources.

Q.77    If, when executing a "READ INTO" command, the length of actual (variable) length record exceeds the length specified in LENGTH option, what will happen (if anything)?

A          You will get a LENGERR.

Q.78    When a second READ WITH UPDATE is given against the same file in the stripe task prior to releasing the file, what will happen?

A          An INVREQ will take place.

Q.79    How could you prevent such an error?

A          After the first read and prior to the second read you could :

             Execute a REWRITE

             Execute a SYNCPOINT

Q.80    Name one condition that would result in the inability to execute a backward browse?

A          If you issue a STARTBR with a generic key, a backward browse will not work.

Q.81    Name one condition that would result in the inability to execute a backward browse?

A          If you issue a STARTBR with a generic key, a backward browse will not work.

Q.82    You have duplicate keys and you have loaded an alternate index into RIDFLD. What would happen if you issued a READNEXT after switching from a direct retrieval read?

A          You would get the same record twice.

Q.83    You are doing a mass delete using a generic key. What could you do to determine the number of records that have been deleted?

A          You would use the NUMREC (data area) option with the generic key. Upon completion of the mass delete, the data area would contain a count of the number of records that were deleted.

Q.84    How should the data area used with the NUMREC option be defined?

A          S9(4) COMP.

Q.85    Which command will terminate a VSAM mass insert operation?

A          An UNLOCK command.

  

Q.86    Which command(s) will deblock DAM files?

A          DEBKEY will deblock by key.  DEBREC will deblock by relative record number.

Q.87    What could cause you to get an INVREQ when building a logical message to a screen?

A          You have changed the disposition specified while building a logical message.

Q.88    What could cause you to get a MAPFAIL when issuing a RECEIVE MAP command?

A          You would get a MAPFAIL if no data was transferred from the screen.

Q.89    What command would you issue if you wanted to discontinue building a logical message?

A          You would issue a PURGE MESSAGE command.

Q.90    Can you intermix a SEND TEXT and a SEND MAP when building portions of a logical message?

A          No, you cannot intermix these two commands.

Q.91    How do you release page buffers?

A          By issuing a FREEMAIN command.

Q.91    What do you have to do to determine if data was sent (from a screen) from a specific (single) field?

A          You have to check the MDT for that field.

Q.92    Which command would you issue to get data in a task that was started by a START command?

A          You would issue a RETRIEVE command.

Q.93    What would happen if you issued a READNEXT TS command and there were no more data in the queue?

A          You would get an ITEMERR.

Q.94    You have a DL/I file and you want to issue a READPREV. Will it work correctly?

A          You can issue a READPREV only against a VSAM file.

Q.95    Can you issue a BROWSE command in a CICS program that is pseudo conversational?

A          Yes, but the BROWSE will terminate at the end of each task in the session, it will not carry over.

Q.96    What are the two ways to "set up” a browse starting with the first record in the file?

A          You can :

·                  Set the complete key equal to hex zeros (the default option is GTEQ).

·                  You can specify KEYLENGTH(0) and GENERIC options.

Q.97    In a VSAM file, when you want to do a mass delete, the file has to be unprotected. How can you specify to the system that a file is unprotected?

A          In the FCT you set LOG = NO.

Q.98    When you are sending your first data screen to the terminal, it is recommended that you specify the ERASE option.  Why?

A          If you do not include the ERASE option, the screen size will be the same as the previous screen size setting ... and this may not be correct. There may also be material on the screen which would remain if not overlaid by fields of your map.

Q.99    Which key, if depressed by the terminal operator, will set the screen size to its default size?

A          The CLEAR key.

Q.100  Does a HANDLE CONDITION command take precedence over a HANDLE AID command?

A          No, the HANDLE AID takes precedence.

Q.101  What does the BMS ROUTE command do?

A          The ROUT E command initiates the building of a logical message that will be scheduled for delivery to one or more terminals.

Q.102  What has happened if you abend with an “APCT"?

A          The program tried to execute a program that was either :

·                  Not defined in the PPT or active RDO group

·                  Disabled

Q.103  What does the ERASEUP command do?

A          The ERASEUP command includes :

·                  Clears all MDTs

·                  Unlocks the keyboard

·                  Erases all unprotected fields

·                  Positions the cursor at the first unprotected field

Q.104  What will happen if you issue an XCTL or a LINK and the called program cannot be found?

A:         You will get a PGMIDERR.

Q.105  What happens to the exception (HANDLE CONDITION, HANDLE ABEND, HANDLE AID) condition settings in a called routine once control has been transferred to the called routine?

A          Once you are in the called routine, all condition settings are deactivated.

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