Designing the Storage Class Routine for IMS Data

The HLQ identifies IMS™ data sets and the LLQ identifies data types requiring specialized performance and availability services. Figure 1 shows the FILTLIST section of the storage class ACS routine that identifies IMS database data sets for special services.

Figure 1. FILTLIST Section for IMS from Storage Class ACS Routine

FILTLIST SPECIAL_USERS       INCLUDE('SYSPROG','STGADMIN','DBA')
FILTLIST VALID_STORAGE_CLASS INCLUDE('BACKUP','CRITICAL','FAST','FASTREAD',
                                     'FASTWRIT','GSPACE','MEDIUM','NONVIO',
                                     'STANDARD','DBCRIT')
/**********************************************************************/
/*             Start of IMS-related FILTLISTs                         */
/**********************************************************************/
FILTLIST IMS                 INCLUDE(%IMS*.**)
FILTLIST IMS_PROD_DL1        INCLUDE(PIMS*.PAYROLL.DB.*)
FILTLIST IMS_PROD_LMSG       INCLUDE(PIMS*.**.LGMSG)
FILTLIST IMS_PROD_OLDS       INCLUDE(PIMS*.**.OL*)
FILTLIST IMS_PROD_QUEUE      INCLUDE(PIMS*.**.QBLKS)
FILTLIST IMS_PROD_RECON      INCLUDE(PIMS*.**.RECON)
FILTLIST IMS_PROD_RESTART    INCLUDE(PIMS*.**.RDS)
FILTLIST IMS_PROD_SMSG       INCLUDE(PIMS*.**.SHMSG)
FILTLIST IMS_PROD_SPA        INCLUDE(PIMS*.**.SPA)
FILTLIST IMS_PROD_WADS       INCLUDE(PIMS*.**.WADS*)
/**********************************************************************/
/*             End of IMS-related FILTLISTs                           */
/**********************************************************************/

This is a common section run before processing IMS database data sets by type. It lets system programmers, database and storage administrators assign storage classes externally, and even allocate these data sets as non-system-managed. Figure 2 shows the ACS code.

Figure 2. ACS Code to Permit Special Users to Override SMS Allocation

  WHEN (&GROUP = &SPECIAL_USERS &&         /*  Permit storage admin., */
        &STORCLAS = &VALID_STORAGE_CLASS)  /*  system programmers,    */
    DO                                     /*  and DBAs to specify    */
      SET &STORCLAS = &STORCLAS            /*  a storage class        */
      EXIT
    END
  WHEN (&GROUP = &SPECIAL_USERS &&         /*   Permit storage admin. */
         &STORCLAS = 'NONSMS')             /*   or data base admin.   */
    DO                                     /*   to create             */
      SET &STORCLAS = ''                   /*   non-system-managed    */
      EXIT                                 /*   data sets             */
    END

Figure 1 shows the logic to process IMS database data sets by type. Only production database data sets are assigned specialized services in this routine. The first character of the data set's HLQ defines a production (P) or test (T) database data set. The three low-order characters of the HLQ are set to IMS. The DSN mask defined in the FILTLIST section for the data set type describes the data set type in the LLQ. Consider the following when deciding on your naming conventions:

The first WHEN clause verifies that the data set belongs to an IMS system, by checking the FILTLIST variable, IMS
Each uniquely named data set type is assigned the recommended storage class
Any IMS production database data set not specifically identified, or any test IMS database data set, is assigned STANDARD storage services.