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 O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.