Parameter in IEASYSxx (or supplied by the operator)

MSTRJCL=(xx[,L])

The two characters (A-Z, 0-9, @, #, or $), represented by xx, are appended to MSTJCL to identify one of the following:

The MSTJCLxx member of SYS1.PARMLIB.
The MSTJCLxx module in SYS1.LINKLIB.

If the MSTRJCL parameter is not specified, the system uses the MSTJCL00 parmlib member. If the system does not find the MSTJCL00 parmlib member, it uses the default master JCL in the MSTJCL00 module in SYS1.LINKLIB.