CICS - Customer Information Control System

Customer Information Control System.

CICS® stands for Customer Information Control System, is a world−class transaction processing system. 

It is a all-purpose transaction processing system for the z/OS® operating system. 

Customer Information Control System deliver services for running an application online, by request, at the same time as many other users are submitting jobs/requests to run the same/different applications, using the same data files and programs.

As such, CICS can handle millions of the transactions from hundreds of users at the same time as they run a variety of application programs. 

Customer Information Control System (CICS) loads corresponding programs, coordinates their execution, manages the data transmissions between multiple programs and terminals, controls the access to data, and at the same time maintains the integrity of that data. Because Customer Information Control System (CICS) is a world class transaction processing system, it can be called online transaction processing (OLTP) software.

"The world’s class leading application server software for IBM Z – serving 1.2 million transactions per second."

"Walmart runs an average of 500 million transactions per day on CICS… and up to a 10:1 cost ratio over comparable solutions."

To a large extent, then, Customer Information Control System (CICS) is an operating system in itself because it provides many of the services mainly associated with an z/OS operating system. For example, CICS manages its own processor storage, provides its own file management functions, and includes a task manager that handles the concurrent execution of multiple programs. Thus, Customer Information Control System (CICS) runs under OS/390 or VSE/ESA, you can think of CICS as an operating system within an operating system.

Customer Information Control System

CICS acts as an interface between the application programs and the operating system's services. So when the application program wants to access a terminal or a disk device, it doesn't communicate directly with the device. Instead, it issues commands to communicate with CICS, which communicates with one of the operating system's access methods. Then, the access method communicates with the device. This shelters your application programs from a specific device and operating system details.