Defining Your Subsystem

If you want to use dynamic SSI services, your subsystem must be defined to MVS™ in one of the following ways:

IEFSSNxx parmlib member (keyword format) processing during IPL
IEFSSI macro invocation
SETSSI system command invocation.

The maximum number of subsystems you can define is 32,767.

If you do not want to be able to use dynamic SSI services, your subsystem must be defined to MVS at IPL time in the positional format of the IEFSSNxx parmlib member.

See z/OS MVS Initialization and Tuning Reference for detailed information on the syntax and rules for coding IEFSSNxx. See z/OS MVS Programming: Authorized Assembler Services Reference EDT-IXG for information on the syntax and rules for coding the IEFSSI macro. See z/OS MVS System Commands for information on the syntax and rules for issuing the SETSSI system command.

There are some special things to think about when defining your subsystem, including:

Naming your subsystem
Passing parameters
The primary subsystem