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Concatenation Notes

A few notes on how z/OS determines the logical Parmlib concatenation:

• In relation to master JCL, the SYS1.LINKLIB and SYS1.PARMLIB data sets referenced in the previous section, Parameter Library, are the single, actual data sets by these names, and not the system linklist concatenation or the logical Parmlib concatenation.
• PARMLIB statements (if present) within the LOADxx member, will always override IEFPARM DD statement information contained in the master JCL member used.
• You can override the default master JCL MSTJCLxx member MSTJCL00 at the console at IPL time by specifying the following:

  MSTRJCL=nn
  

  Where nn identifies the suffix of the MSTJCLxx member to be used.

• Invalid or missing data sets names in MSTJCLxx members will cause the IPL to fail while invalid or missing data set names in a LOADxx member’s PARMLIB statements may cause an error and possible prompt at the console, but generally, it’s possible for the IPL to continue.
• You can concatenate up to 120 data sets under the IEFPARM DD statement in MSTJCLxx members and up to 16 data sets under the LOADxx member’s PARMLIB statement (plus one for SYS1.PARMLIB). The SYS1.PARMLIB data set is automatically added to the end, if it is not already defined.

  In either case, both are limited by DF/SMS to a maximum of 120 DASD extents which can be allocated to a concatenated PDS. It is important to monitor the number of DASD extents for critical system data sets.

  Exceeding these limits will cause the IPL to fail, so it’s important to monitor the number of DASD extents for critical system data sets. The data sets will be discarded in error when a LOADxx member is used at IPL time. When used after IPL through the SETLOAD command, the SETLOAD command will fail in this instance.

• Only partitioned data sets (PDS) can be specified within the MSTJCLxx member’s IEFPARM DD statement. The same restriction is true for LOADxx members that are used initially during the IPL process. However, you can use the SETLOAD command to specify one or more partitioned data set extended (PDSE) data sets in a LOADxx member that is used after IPL.