Data Set Compression Exit: ZCOMP

Topics:

The ZCOMP Exit applies to VSAM, ISAM, CISAM, RMS and other SAM type data structures, and to certain FIX structures.

Three functions plus a main entry point comprise the compression exit, collectively known as the ZCOMP Exit. The main entry point is ZCOMP which exports:

  • ZCOMP0 for initial housekeeping.
  • ZCOMP1 for the actual processing. It is designed so customers can access and decrypt coded fields, expand compressed records, and accomplish other specified data manipulations.
  • ZCOMP2 is called to perform clean-up when the session is over.

Anchor storage is passed to ZCOMP0, ZCOMP1 and ZCOMP2 to maintain persistence and reentrancy.

The ZCOMP reference code is supplied, However, the actual DLL is expected to be user-written, and maintained to fit the specific need. The exit must be compiled and linked in accordance with standard user-written exit procedures.

There are no special Master File coding requirements to use ZCOMP. The SUFFIX value can be VSAM (for KSDS or ESDS files), CISAM, RMS, FIX (for sequential files), or PRIVATE (for file access through the GETPRV user exit).


WebFOCUS