DFSMSdfp Installation Exits

Table 1 describes DFSMSdfp installation exits used for either system-managed or non-system-managed data.

Table 1. DFSMSdfp Installation Exits
Name	Usage
IFG0EX0A	OPEN/EOV Exit for VTOC Entry Not Found: Non-system-managed volumes. Called in OPEN or EOV if the VTOC entry is not found on the volume. If you already have DFSMShsm installed or intend to install it, be aware that a DFSMShsm-supplied exit routine recalls a data set if the VTOC entry is not found because the data set has been migrated. The data set that the user is attempting to allocate might be a migrated system-managed data set. If the exit is taken, an OPEN error occurs, indicating that the data set could not be found on the volume. To prevent this situation from occurring, physically remove the volume from the system and define it to a DUMMY storage group.
IFG0EX0B	DCB OPEN Exit: Non-system-managed data sets. Because IFGOEXOB exit is called before OPEN, you can mark the data set as reblockable. To do this, preserve the existing data set's block size and exit with condition code 12. This tells DFSMSdss to use the system-determined block size, and sets the reblockable indicator. Some data sets (for example, load libraries) are sensitive to reblocking. Use care when reblocking them.
IGBDCSX1 and IGBDCSX2	DASD Calculation Services Exits: Non-system-managed data. These pre-DASD calculation services (DCS) exits and post-DCS exits provide some flexibility in, and control over, the selection of optimum VSAM control interval (CI) size or non-VSAM block size. The block size you return is used not only by DFSMSdss, but also for all reblockable data sets. Recommendation: Because DFSMS selects the optimum block size for each device type, do not use exits IGBDCSX1 and IGBDCSX2.
IGGPRE00	DADSM Preallocation Exit routine associated with the IGGPRE00_EXIT dynamic exit: Non-system-managed data. It is a common practice to use the IGGPREOO exit to restrict allocation on specific volumes. Do not use this exit for system-managed data sets. See z/OS DFSMS Installation Exits for further information.
IGDACSDC IGDACSSC and IGDACSMC	Data, Storage, and Management Class ACS Routine Exits: Data class ACS Routine Exit applies to system-managed and non-system-managed data. Storage and management class ACS Routine Exits apply to system-managed data. Called after the data, storage, and management class ACS routines have been run. Can override the name of the class assigned by its ACS routine. Can request that an ACS routine be reentered. Parameters passed to these exits are the same as those available to the ACS routines. Do not code any of these exits unless you require special processing that is not available in an ACS routine. Dummy exits degrade performance. Special processing could include functions such as calling other programs, writing SMF records, or writing generalized trace facility trace records.
IGDACSXT	SMS pre-ACS exit: Used by a tape management system Can set the &MSPOOL, &MSPOLICY, &MSDEST, and &MSPARM read-only variables to the ACS routines Parameters passed onto this exit are the same as those available to the ACS exits.