A functional subsystem (FSS) is an address space dedicated to performing a specific function. For example, the Print Services Facility™ is used as a functional subsystem to operate the 3800 Model 3 and 3820 printers. You can dynamically define an FSS to JES2 using the $ADD FSS command or change the characteristics of an existing FSS definition using the $T FSS command.

The parameters are the same for both commands. You specify the name of the FSS, the name of the JCL procedure used to start the FSS, and the name of the module that is loaded into the FSS address space. The load module contains the various JES2-supplied interface routines. The AUTOSTOP parameter specifies whether or not JES2 is to automatically stop the address space when the devices attached to the FSS are drained. See the individual command descriptions in for the particular processing considerations associated with these commands.