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.