IEFSSNxx (subsystem definitions) - positional parameter form

Note: This appendix describes the IEFSSNxx parmlib member in the positional parameter form. IBM® suggests that you use the IEFSSNxx parmlib member in the keyword parameter form instead, which allows subsystems defined in the member to use the dynamic SSI services.

IEFSSNxx is a parmlib member that contains parameters defining the primary subsystem and the various secondary subsystems that are to be initialized during system initialization. IEFSSNxx allows you to name the subsystem initialization routine to be given control during master scheduler initialization. IEFSSNxx also allows you to specify the input parameter to be passed to the subsystem initialization routine. Using the PRIMARY keyword, you can specify a primary subsystem name. The NOSTART keyword used with the PRIMARY keyword indicates that the system is not to issue an automatic start for the primary subsystem.

For information about writing subsystems, see z/OS MVS Using the Subsystem Interface.

The order in which the subsystems are initialized depends on the order in which they are defined in the IEFSSNxx parmlib member on the SSN parameter. Unless you are starting the Storage Management Subsystem (SMS), start the primary subsystem (JES) first. Some subsystems require the services of the primary subsystem in their initialization routines. Problems will occur if subsystems that use the subsystem affinity service in their initialization routines are initialized before the primary subsystem. If you are starting SMS, specify its record before you specify the primary subsystem record.

The format of the IEFSSNxx record for SMS is described in Defining SMS through the IEFSSNxx member.