Dynamic Installation of the FDR Exits
New installations
If your FDR system includes ABR and/or FDRREORG, you will probably want to activate the appropriate FDR system exits, using the dynamic exit installation described in the following sections. These exits can be installed and deactivated as required during your testing. When testing is complete, follow the procedures described to insure that the exits are installed following every IPL.
Existing installations
If your FDR system includes ABR and/or FDRREORG, you will want to test the new version of the exits. Procedures for testing the new exits while continuing to run the exits from the prior release of FDR are described in the following sections; you can restrict the test exits to certain users or jobs. Once the new FDR is installed for production, be sure to follow the procedures for activating the new exits for use by all users and be sure that the new exits are installed after every IPL.
The FDR system includes several Operating System exits. Although these exits are not required for ABR to function, they provide important additional functions. They are installed by a dynamic installation process that is transparent to other system functions. The ABR Operating System exits are installed at well-defined exit and interface points provided by z/OS whenever possible, and are designed to co-exist with other exits that may already be in use at the same exit points.
The dynamic installation process enables the FDR Operating System exits to be automatically installed at IPL time and to remain throughout the life of the IPL. Once installed, the exits may be deactivated and reactivated, possibly with different installation options.
Exits that are installed dynamically
The ABR z/OS exits that are available for dynamic installation are the ABR Catalog Locate exit and the Data Set Not Found (DSNF) exit, which implement the Automatic Recall feature of ABR, the DADSM Pre-processing exit and the FDRREORG IEBCOPY intercept.
Exits for automatic recall
The ABR Catalog Locate exit (module FDR026DU) and the ABR Data Set Not Found exit (module FDREXDSN) implement the Automatic Recall feature of ABR, which is discussed in detail in FDRABR-Archiving-and-Superscratch. With these exits installed, a reference to a data set that has been archived, from either a batch job or a TSO user, will cause the data set to be automatically restored. If these exits are not installed, any restore of an archived data set must be explicitly requested.
The ABR Data Set Not Found exit is required only if you need to archive and auto-recall uncataloged data sets, or if you have jobs that reference cataloged data sets on specific volumes using UNIT= and VOL= (bypassing the catalog). If neither of these applies, you need install only the ABR Catalog Locate exit to implement auto-recall.
When the ABR Catalog Locate exit is installed, three other supporting exits are also installed: FDRDAS02 (a DADSM scratch exit to suppress irrelevant messages associated with deleting archived GDGs), FDR00024 (to implement transparent support for recall requests using the DFSMShsm interfaces), and FDRDYNEX (to support dynamic LPA support for DADSM and load modules). In addition, if there is no module called ARCGIVER (a DFSMShsm module involved in the DFSMShsm interface) a module called FDRGIVER is installed.
DADSM pre-processing exit
The purpose of the ABR DADSM pre-processing exit (module FDRPRE00) is to record ABR backup information in the ABR SCRATCH catalog for any data sets that are scratched (deleted) or renamed by programs other than FDRABR if they have current ABR backups. With the DADSM Pre-processing exit installed, a user can request the restore of a data set that has been scratched or renamed simply by specifying the data set name. If this exit is not installed, the backups are still available, but the user must tell ABR the generation and cycle from which to restore a scratched data set
When a data set is renamed, the DADSM Pre-processing exit clears the ABR backup indicators to indicate that the data set has not been backed up under the new name. When a new data set is allocated, or a data set is extended to a new volume, this exit initializes the last reference date.
When FDRPRE00 is installed, a second exit (FDRPOST0, a DADSM Post-Processing exit) also appears to be installed; actually, it is an additional entry point in FDRPRE00. Additionally, in z/OS 1.13 and above, an additional exit (FDRDYXCS) is installed to support calling the FDRPRE00 and FDRPOST0 exits.
FDRREORG IEBCOPY intercept
FDRREORG can provide an optimized replacement for an IEBCOPY compress-in-place operation providing substantial savings in elapsed time and resource consumption. This intercept enables FDRREORG to transparently replace IEBCOPY compress operations. When installed, any invocation of IEBCOPY will actually invoke the intercept. The intercept will determine if the user requested a compress-in-place. If so, an FDRCOPY REORG is invoked to compress the data set. Other IEBCOPY functions are passed to the real IEBCOPY. The intercept will also handle programs that call IEBCOPY for compression, such as SMP/E, and ISPF.