System Installation Choices › Parmlib Information

Parmlib Information

Most of the z/OS system options and parameters are specified in the system parameter library (parmlib, or logical parmlib). Parmlib members determine the SMF options, the APF library list, the LPA library list, the link library list, appendages, subsystems, and contents of FLPA and MLPA for the system. Parmlib is made up of various members, which can exist in multiple data sets concatenated together as part of what is called the logical parmlib. The logical parmlib contains both the master (IEASYSxx) members, as well as any members referenced by the master IEASYSxx members.

The Parmlib Information option (2.1) helps you analyze the contents of the logical parmlib library. With this function, you can:

• Detect when each member of the logical parmlib was last changed
• Display a map of the logical parmlib members and their referenced members
• List the master members and the members each controls
• Determine the purpose of each member
• Browse each member of the logical parmlib
• Display the contents of the logical parmlib concatenation in use on this system
• Display the system LOAD parameters for the current system IPL, and specify different LOAD parameters to allow analysis of a different logical parmlib structure (such as for a different system, an alternate SYSRES volume).

The parameter library contains the options and parameters that tailor a data center’s configuration and resources. As the data center’s needs change, these parameters can also change. You should closely monitor Parmlib members because they play a major part in the control of performance and security.

The z/OS logical parmlib provides a central location for the specification of z/OS system options and parameters. During system initialization (IPL), the system reads the parameter information in SYS1.PARMLIB and logical parmlib data sets. It combines this information with other system operator commands entered during IPL. The SYS1.PARMLIB library and other logical parmlib data sets can reside on the system residence (SYSRES) volume. Alternatively, the data center can catalog the library, and the system determines the library location from the catalog.

The logical parmlib contains a master member, IEASYS00. The logical parmlib also contains general members (identified by the prefix IEASYSxx) and specialized members to which general members refer. General members are like alternate master members. At IPL, the operator might specify a master member suffix, or one might be defined in the system LOADxx member that is identified by the eight-character LOADPARM value specified at IPL. The general members to which this master member refers are merged with the master member. However, the operator can override the merging of selected general members. This merge specifies the options and parameters that define the subsystems, SMF options, APF libraries, I/O appendages, and so on. The process of merging master and general Parmlib members is described in the IBM z/OS MVS Initialization and Tuning Guide and z/OS MVS Initialization and Tuning Reference.