1.6. VSAM data set organizations

VSAM arranges records by index key, relative record number, or relative byte address. It is used for direct or sequential processing of fixed-length and variable length records on DASD. VSAM data is cataloged for easy retrieval. VSAM supports five data set organizations:

  • Key-sequenced data set (KSDS)

  • Entry-sequenced data set (ESDS)

  • Relative record data set (RRDS), of which there are two types:

    • Fixed-length relative record data set (RRDS)

    • Variable-length relative record data set (VRRDS)

  • Linear data set (LDS)

  • HFS files

1.6.1. Key-sequenced data set

In a KSDS organization, records are initially loaded in the data component in ascending collating sequence by key. The key contains a unique value that determines that record’s ...

Get VSAM Demystified now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial