This topic discusses the parmlib concatenation, its purpose, ways to control the parmlib data set(s), and general syntax rules for creating most members of the data set(s). Table 1 contains an overview of all the parmlib members.
The parmlib concatenation is a set of up to 16 partitioned data sets defined through PARMLIB statements in the LOADxx member of either SYSn.IPLPARM or SYS1.PARMLIB which contains many initialization parameters in a pre-specified form in a single logical data set, thus minimizing the need for the operator to enter parameters. SYS1.PARMLIB makes the 17th or last data set in the concatenation and is the default parmlib concatenation if no PARMLIB statements exist in LOADxx. For specific information about how to define a logical parmlib concatenation, see LOADxx (system configuration data sets). The SYS1.PARMLIB data set itself can be blocked and can have multiple extents, but it must reside on a single volume. The parmlib concatenation used at IPL must be a PDS. However, after IPL you may issue a SETLOAD command to switch to a different parmlib concatenation which contains PDSEs. For information about processing of concatenated data sets see z/OS DFSMS Using Data Sets.
Parmlib contains both a basic or default general parameter list IEASYS00 and possible alternate general parameter lists, called IEASYSaa, IEASYSbb, and so forth. Parmlib also contains specialized members, such as COMMNDxx, and IEALPAxx. Any general parameter list can contain both parameter values and "directors". The directors (such as MLPA=01) point or direct the system to one or more specialized members, such as IEALPA01.
The parmlib concatenation is read by the system at IPL, and later by other components such as the system resource manager (SRM), the TIOC, and SMF, which are invoked by operator commands. The TIOC is the terminal I/O coordinator, whose parameters are described under member IKJPRM00. SMF is the System Management Facility whose parameters are described under member SMFPRMxx.
The operator selects the IEASYSxx member using the SYSP parameter at IPL. The parameter values in IEASYS00 remain in effect for the life of an IPL unless they are overridden by parameters specified in alternate IEASYSxx members or by the operator. See Step 2. Determine where to specify system parameters for details about how the system processes system parameter specifications.