The exits must follow standard linkage conventions. They must save the registers on entry and restore the registers when they return. The exits must be reentrant, refreshable, and reusable.

If the processing done in the initialization exit requires clean-up to be performed, you must write a termination exit. For example, if the initialization exit obtains storage to return a new command buffer to the TSOLIB command processor, you must provide a termination exit to free this storage.

The exits can use any of the TSO/E service routines. For a description of the service routines, see .