Page mode loading

Program objects can be loaded in Page Mode.

This mode is the default, unless any of the conditions described below under Move Mode exist. Program objects are mapped into virtual storage. If the program object is less than 96K the whole program is preloaded. When over 96K the first 16 pages are preloaded; additional pages are brought in during execution as they are referenced.
Program objects can be cached in the PDSE hiperspace cache, so frequently referenced pages will be found in cache.
When the entire module is read in and relocated before execution begins, it is referred to as Immediate Mode, a subset of Page Mode.
An option, FETCHOPT=PRIME, allows you to specify explicitly that the module should be completely relocated before execution. This option only affects Page Mode and forces Immediate Mode. It has the benefit that the loader can immediately release all storage resources that would otherwise be used to contain loader control information (and would usually be held until the module is deleted). It has the disadvantage of bringing in the entire module when it might not be necessary.

Note: Page mode loading is not supported for program objects loaded from z/OS UNIX files.