Using parmlib concatenation (logical parmlib)

You can concatenate up to 16 data sets to SYS1.PARMLIB, in effect creating a logical parmlib. You define the concatenation in the LOADxx member of SYS1.PARMLIB or SYSn.IPLPARM. Programs can use the IEFPRMLB macro to obtain the parmlib concatenation data set list, allocate and open the parmlib data sets, read a specified parmlib member, and close and unallocate the parmlib data sets. In addition, the operator, if desired, can use a SETLOAD command to switch from one logical parmlib to another without an IPL.

The overriding benefit of using parmlib concatenation is that it gives you greater flexibility in managing parmlib. Specifically, it lets you:
  • Separate IBM-supplied members from locally-customized ones
  • Separate members based on job responsibility and security requirements
  • Separate members for change-management purposes.
If you install using ServerPac or SystemPac, the IBM-supplied defaults cause the following concatenated parmlib data sets to be searched in the order shown when you IPL the target system:
  1. SYS1.PARMLIB (either the SYS1.PARMLIB supplied by IBM® and edited by you or your original SYS1.PARMLIB updated appropriately)
  2. CPAC.PARMLIB (supplied by IBM and customized for your ServerPac or SystemPac order)
  3. SYS1.IBM.PARMLIB (supplied by IBM).

For more information about specifying parmlib concatenation, see z/OS MVS Initialization and Tuning Reference.