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Parameter Library

The system logical Parmlib parameter library (2.1), often referred to as SYS1.PARMLIB or simply parmlib, is the source of many of the system’s initialization options and as such is a very critical element of the audit process.

The logical Parmlib consists of one or more partitioned data sets (PDS) that provide a single location for the specification of most z/OS options and parameters. This information is read during an initial program load (IPL) and again in response to operator commands. It is combined with other supplemental information that the computer operator supplies during the IPL process.

The logical Parmlib is usually specified through PARMLIB statements in the system LOADxx member (specified at IPL time through the LOADPARM value). You can also specify the logical Parmlib definitions through the master scheduler JCL (MSTJCLxx) used at IPL time.

The MSTJCLxx members can exist as data-only load modules link‑edited into the SYS1.LINKLIB data set and as members in the SYS1.PARMLIB data set. In either case, the logical Parmlib contents are specified through the IEFPARM DD statement. If this statement is not provided, the default is to use SYS1.PARMLIB, which must be cataloged and reside on the SYSRES or the IODF DASD volume. A default MSTJCL00 member is provided as part of SYS1.LINKLIB. It does not have an IEFPARM DD statement, so SYS1.PARMLIB is used by default.

You can use the IEEMSJCL source member to customize your installation requirements, and then assemble it using the high‑level assembler and link‑edit it into SYS1.LINKLIB. You should rename this member to something other than MSTJCL00. The IBM-supplied default module should never be altered for any reason. Alternatively, you can create an MSTJCLxx member in SYS1.PARMLIB. If identically named MSTJCLxx members exist in both SYS1.LINKLIB and SYS1.PARMLIB, the SYS1.PARMLIB is checked first, followed by SYS1.LINKLIB.