z/OS data

If you have been using zEDC with the zEDC Express adapter, review your definitions for restrictions that you might remove, to apply compression more broadly. For example:

• Compression of sequential data sets that is selectively enabled by application
• For migration to tape, balancing zEDC against data set compression. Consider removing any restrictions on what you compress.

If you have not been using zEDC, plan for and implement compression:

• At the data set level, using the COMPACTION option of a data class.
• At the system level, using the COMPRESS parameter in the IGDSMSxx member of parmlib, which defines options for the storage management subsystem (SMS)
• During DFSMShsm and DFSMSdss processing, using the ZCOMPRESS parameter of the SETSYS command
• Of dump data, using the ZCOMPRESS parameter of the DEFINE DUMPCLASS command.

Space requirements: To allocate a zEDC compressed format data set, the allocation amount must also meet this minimum space requirement:

• 5 MB minimum primary space amount if a secondary amount is specified
• 8 MB if a secondary amount is not specified.

If the minimum space requirement is not met, the allocation request might result in a non-compressed extended format data set.

Assessing compression: After your definitions are complete and your applications have run, you can assess compression with:

• SMF record type 30
• RMF EADM reporting (RMF 74.10).

For more information, see Assess compression of z/OS data.