PTF SYSMOD: Preventing or fixing problems with an element

When a problem with a software element is discovered, IBM® supplies its customers with a tested fix for that problem. This fix comes in the form of a program temporary fix (PTF). Although you may not have experienced the problem the PTF is intended to prevent, it is wise to install the PTF on your system. The PTF SYSMOD is used to install the PTF, thereby preventing the occurrence of that problem on your system.

Usually, PTFs are designed to replace or update one or more complete elements of a system function. Look at Figure 1, which shows a previously installed load module, LMOD2. To replace the element MOD1, you would install a PTF SYSMOD that contains the module MOD1. That PTF SYSMOD replaces the element in error with the corrected element.

Figure 1. Preventing problems with an element

As part of the installation of the PTF SYSMOD, SMP/E relinks LMOD2 to include the new and corrected version of MOD1.

Figure 2 shows an example of a simple PTF SYSMOD.

Figure 2. Example of a simple PTF SYSMOD

 
 ++PTF(PTF0001)              /* SYSMOD type and identifier.   */.
 ++VER(Z038) FMID(FUN0001)   /* Apply to this product.        */.
 ++MOD(MOD1)                 /* Replace this module           */
             DISTLIB(AOSFB)  /* in this distribution library. */.
  ...
  ... object code for module
  ...

PTF SYSMODs are always dependent upon the installation of a function SYSMOD. In some cases, some PTF SYSMODs may also be dependent upon the installation of other PTF SYSMODs. These dependencies are called prerequisites.

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

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

Sometimes a PTF or even an APAR is dependent upon other PTF SYSMODs called corequisites. 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.