IEAPAKxx can be found in the PARMLIB and contains groups of names of modules in the LPALST concatenation that are executed together or in sequence.
IEAPAKxx is used only during a “cold” start (CLPA specified), when the PLPA is loaded from the LPALST concatenation.
The system uses the specified IEAPAKxx member(s) to determine the order in which modules are to be loaded from the LPALST concatenation into the Pageable LPA. These modules are packed together, if possible, on a single page. The purpose is to reduce page faults. The LPA can greatly contribute to page faults because it is highly used.
The affinity of programs for each other and the size of the programs determine which should be selected for a pack list entry. Program affinity means that one program will usually refer to another program when the first program is invoked. By putting programs that refer to each other into the same pack list entry, and thereby on the same page, extra page faults are avoided, because the programs are always in storage together.