SYSMOD prerequisites

As you have learned, PTF, APAR, and USERMOD SYSMODs all have the function SYSMOD as a prerequisite. In addition to their dependencies on the function SYSMOD:

PTF SYSMODs may be dependent upon other PTF SYSMODs.
APAR SYSMODs may be dependent upon PTF SYSMODs and other APAR SYSMODs.
USERMOD SYSMODs may be dependent upon PTF SYSMODs, APAR SYSMODs, and other USERMOD SYSMODs.

Consider the complexity of these dependencies. When you multiply that complexity by hundreds of load modules in dozens of libraries, the need for a tool like SMP/E becomes apparent.

Let's examine the impact of these dependencies on the maintenance of software in a z/OS® environment.