Sunday, 4 August 2013

VSAM IDCAMS Program – One Stop Shopping For All Functions!

VSAM (Virtual Storage Access Method) is a data management system introduced by IBM in the 1970s as part of the OS/VS1 and OS/VS2 operating systems.

It is an high performance access method used in IBM mainframe OS.

Access Method Service is a service program that helps in allocating, maintaining deleting catalogs and data sets.

IDCAMS is only a single utility for managing all of the housekeeping needs of VSAM. In-fact it is right to say that IDCAMS is a one single stop for all function!

IDCAMS - Basic Access Method Services Functions

  • VSAM objects may only be created by using the utility Access Method Services - One group of commands create VSAM definitions via the “DEFINE” 
  • The term defining  means creating an entry in the z/OS Catalog without data transfer
  • The contents of an object can be loaded via IDCAMS or a user program.
  • The IDCAMS program provides all functions to manipulate VSAM Objects.

Basic Access Method Services Functions

ALTERChanges attributes in the VSAM Catalog for previously defined VSAM objects.
BLDINDEXSorts and loads pointer (alternate key) information into a newly defined alternate index.
DEFINEDefines VSAM objects, such as catalogs, clusters, non-VSAM and other data structures.
DELETEPurges VSAM and other data structures from catalog
DIAGNOSEChecks entries in a BCS and/or VVDS for validity and consistency.
EXPORTCopies a VSAM data-set with related catalog information to a sequential data set.
IMPORTImports and reorganizes a VSAM data set which was previously exported by EXPORT.
LISTCATLists VSAM catalog information
PRINTPrints contents of VSAM data-sets and non-VSAM
REPROLoads, copies, converts, merges, reorganizes data sets and catalogs
VERIFYUpdates catalog high-used RBA information for a VSAM data-set which was not closed in a normal way.

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