Your subsystem can use the SSI function code 4 to clean up any resources for a task that is associated with a particular subsystem, and free any resources not normally handled by a resource manager.

Because your function routine gets control for every End-of-Task call, using your own subsystem may not be the most efficient way to do your own clean up for ending tasks. IBM® recommends that you define your own resource manager through the use of the RESMGR macro. RESMGR can be used to monitor specific ending tasks, rather than having to check each ending task or address space to see if it used the subsystem. For a general description of resource managers and how they can be defined at both IPL time and dynamically, see z/OS MVS Programming: Authorized Assembler Services Guide.