Example

In Figure 1, the macro instruction at ALLOCINF creates a parameter list for one DCB (INDCB), assumed to be open for input. The JFCBs and volume serial numbers are retrieved for all data sets allocated to DDNAME SYSLIB.

Figure 1. Sample Code Retrieving Allocation Information Part 1 of 2

    ***JCL FOR FOLLOWING INVOCATION OF RDJFCB:
     //SYSLIB DD    DISP=SHR,DSN=DEPT61.MACLIB
     //       DD    DISP=SHR,DSN=CORPORAT.MACLIB
     //       DD    PATH='/projects/sasp/maclib',PATHOPTS=ORDONLY
     //       DD    DISP=SHR,DSN=SYS1.MACLIB
       ***EXAMPLE CODE TO INVOKE RDJFCB ALLOCATION INFORMATION RETRIEVAL:
     *   GET A COPY OF THE JFCB FOR THE FIRST OR ONLY DATA SET ALLOCATED
     *   TO SYSLIB AND TRY TO READ THE JFCBS VOLUME SERIAL NUMBERS
     *   AND PATH NAMES FOR ALL DATA SETS ALLOCATED TO SYSLIB.
     *
     ALLOCINF RDJFCB (INDCB)
              LTR   R15,R15          TEST RDJFCB RETURN CODE
              BNZ   NOJFCB           BRANCH IF INFORMATION NOT AVAILABLE
              ICM   R1,X'F',SLBAREA  GET AND TEST ADDRESS OF ARL
              BZ    OLDSYSTM         GO IF SYSTEM DOES NOT SUPPORT ARL
              CLI   SLBRCODE,0       TEST RDJFCB REASON CODE
              BNE   NOJFCB           BRANCH IF INFORMATION NOT AVAILABLE
     *
     *  LOOP THROUGH THE JFCBS IN THE AREA TO WHICH SLBAREA POINTS.
     *  CODE CAN BE INSERTED HERE TO PRINT THE DATA SET NAMES, VOLUME SERIAL NUMBERS
     *  AND PATH NAMES.
              L     R9,SLBRTRVD      GET NUMBER OF JFCB'S RETRIEVED
              L     R2,SLBAREA       POINT TO ARA 
              USING ARA,R2
     LOOPARA  TM    ARAFLG,ARAXINF   BRANCH IF NO EXTENDED
              BZ    USEJFCB          INFORMATION SEGMENT
              SR    R3,3             PREPARE FOR IC
              IC    R3,ARAXINOF      GET DOUBLEWORD OFFSET
              SLL   R3,3             GET BYTE OFFSET
              AR    R3,R2            POINT TO EXTENDED INFO SEGMENT
              USING ARAXINLN,R3      EXTENDED INFORMATION SEGMENT
              SR    R4,R4            PREPARE FOR ICM
              ICM   R4,B'0011',ARAPATHO BRANCH IF NO PATH
              BZ    USEJFCB          NAME
              USING ARAPATHNAME,R4
     *  PRINT PATH NAME
               .
               .
              B     NEXTARA
     *  PRINT DATA SET NAME IN JFCB.
     USEJFCB   ...
               .
               .                 
     NEXTARA  AH    R2,ARALEN        POINT TO NEXT ARA ENTRY
              BCT   R9,LOOPARA       DECREMENT JFCB COUNTER, LOOP IF MORE
               .
               .
              SR    R2,R2
              IC    R2,SLBPOOL
              SR    R0,R0
              ICM   R0,B'0111',SLBRLEN
              FREEMAIN RU,LV=(0),SP=(R2),A=SLBAREA
              .
              .

Figure 2. Sample Code Retrieving Allocation Information Part 2 of 2

     OLDSYSTM DS    0H               ROUTINE TO HANDLE JUST LIBJFCB
              .
              .
     *
     NOJFCB   DS    0H               ROUTINE TO HANDLE INABILITY TO GET THE
     *                               JFCB. THE DATA SET MAY NOT BE ALLOCATED.
              .
              .
     *
    
    
     SLBOPNX  DS    0H               DCB OPEN EXIT ROUTINE FOR SYSLIB.
     *                               HANDLES RECFM, LRECL, AND BLKSIZE.
              .
              .
     INDCB    DCB   DSORG=PO,DDNAME=SYSLIB,MACRF=R,SYNAD=INERROR,            X
                    EXLST=INEXLST
     INEXLST  DC    0F'0',AL1(EXLDCBEX)    ENTRY CODE FOR OPEN EXIT ROUTINE
              DC    AL3(SLBOPNX)           ADDR OF DCB OPEN EXIT ROUTINE
              DC    AL1(EXLARL)            ENTRY CODE TO RETRIEVE
     *                                     ALLOCATION INFORMATION
              DC    AL3(SLBSTRT)           ADDR OF ALLOCATION RETRIEVAL LIST
              DC    AL1(EXLLASTE+EXLRJFCB) ENTRY CODE TO RETRIEVE FIRST JFCB
     *                                     AND INDICATE LAST ENTRY IN LIST
              DC    AL3(LIBJFCB)           ADDR OF JFCB FOR FIRST DATA SET
     *
     *  AN ALLOCATION RETRIEVAL LIST FOLLOWS, POINTED TO BY DCB EXIT LIST.
     *
     SLBSTRT  IHAARL DSECT=NO,PREFIX=SLB
              DC    0F'0'
     LIBJFCB  DC    CL176' '         FIRST JFCB
              .                      IHAARA ,
                                     IHAEXLST ,      DCB exit list mapping