Recovery and Integrity

When you write a function routine, IBM® recommends that you provide recovery in case your function routine fails. Your recovery routine should indicate unsuccessful processing, clean up any resources used, and return control to the SSI. You might also want to disable one or more of your supported function codes. See Disabling Previously Supported Functions for more information.

Attention: Because there is no serialization used for updating the function codes in the SSVT, other requests for supported functions might be coming in asynchronously. The SSVT identifies:

The SSI function codes to which the subsystem responds
The subsystem routines that process the supported functions.

Therefore, do not delete a function routine from storage (because a task may be using it) and do not delete the SSVT.