provides replaceable modules or exit points for installation
exit routines that modify system functions. A replaceable
module is an IBM-supplied module that you can modify or replace.
Following are the types of replaceable modules or exit locations
that are defined as installation exits:
- Dummy modules. The IBM-supplied module does not perform a useful
function, it just supplies a return code to its caller. For example,
the DADSM exit routines are dummy modules.
- Functional modules. The IBM-supplied module already performs
a useful function. Although you can replace these modules, carefully
consider whether you should preserve the IBM-supplied functions.
For example, the data management abend installation exit (IFG0199I)
is a functional module.
- No module. IBM does not supply a module, but does supply an exit
point so that you can create an exit routine if you desire. If you
do not supply a routine, the exit is not taken. For example, the
nonstandard tape label processing exit points do not come with a replaceable
module.
Any modules you create for installation exits must be reentrant
and refreshable. You can install them during system installation
by using SMP/E or you can link-edit the module into the appropriate
library.
Installation exits are available at a variety of points in processing.
The sections for each exit documented in this information specify
where in the system's processes the exits are called.