This topic discusses how ICSF callable services use the different key types and key forms. It also provides suggestions on what to do if there is a problem.

ICSF provides callable services that perform cryptographic functions. You call and pass parameters to a callable service from an application program. Besides the callable services ICSF provides, you can write your own callable services called installation-defined callable services. Note that only an experienced system programmer should attempt to write an installation-defined callable service.

To write an installation-defined callable service, you must first write the callable service and link-edit it into a load module. Then define the service in the installation options data set.

You must also write a service stub. To execute an installation-defined callable service, you call a service stub from your application program. In the service stub, you specify the service number that identifies the callable service.

For more information about installation-defined callable services, see z/OS Cryptographic Services ICSF System Programmer’s Guide.