This topic discusses how installation-written exit modules can:
- Take control before and after DADSM processing.
- Take control during open for a DCB.
- Recover from errors that can occur during the opening, closing,
or handling of an end-of-volume condition for a data set associated
with the user's task.
- Bypass, limit, or override system-calculated values that assist
you in selecting optimum DASD data set block size or control interval
size.
- Alter messages sent to 3480, 3490, and 3590 tape operators.
You can substitute your own exit routines for the data management
replaceable modules listed in Table 1.
Table 1. Data Management Replaceable ModulesModule Name |
Description |
When Available |
---|
IFG0EX0B |
DCB open installation exit |
At open |
IFG0199I |
Data management abend installation exit |
Open, close, end-of-volume abnormal conditions |
IGBDCSX1 IGBDCSX2 |
Precalculation and postcalculation exit |
DASD calculation services |
IGGDARU3 |
DADSM RENAME postprocessing exit |
Before exit from RENAME |
IGGDASU3 |
DADSM SCRATCH postprocessing exit |
Before exit from SCRATCH |
IGXMSGEX |
Message display exit |
Before end of tape cartridge message display processing |
The data management replaceable modules you replace must be named
the same as the IBM-supplied modules. In general, the module you replace
must:
- Handle multiple requests (be reentrant).
- Reside in SYS1.LPALIB (or be link-edited into LINKLIB).
- Save and restore registers.
You can also add an exit routine for the data management
dynamic exits listed in Table 2.
Table 2. Data Management
Dynamic ExitsModule Name |
Description |
When Available |
---|
IGGPRE00_EXIT IGGPOST0_EXIT |
DADSM pre-processing and post-processing dynamic exit routine.
The system will add IGGPRE00 and IGGPOST0 as an exit routine to their
respective dynamic exit. |
DADSM create, extend, scratch, partial release and rename functions |
Other products can impact the modifications you install. For example,
RACF®, a component of the Security Server for z/OS, takes
control at the same time as some of the installation exits. They could compete
for resources.