Application Migration Considerations

An existing application can take advantage of these VSAM Data Compression Services without the need for program changes. The compression controls are in the VSAM product and are not tied to the application code. Two things must be done to migrate existing data sets to compressed format:

  1. A 'VSAM.COMPRESS.CONTROL' KSDS compression control data set must be defined in each catalog where compressed data will reside.
  2. The existing data set CLUSTER must be redefined as COMPRESS format.

Use the following examples to assist you in migrating to a compressed format.