IHADECB | Back to Index page

| Prolog Control Block Contents IHADECB DSECT Storage Layout Cross Reference (Contains links to field and bit definitions) |
Programming Interface Information: This page documents intended Programming Interfaces that allow the customer to write programs to obtain the services of z/VM.

IHADECB Prolog | Top of page

     NAME       : CMSCB
     DESCRIPTION: DATA EVENT CONTROL BLOCKS FOR
                  BSAM, BISAM, BDAM, QTAM, BTAM.
     DSECT      : IHADECB
     FUNCTION   : IHADECB is the simulated data event control
                  block used for CMS processing of OS macros and
                  OS access methods. The IOBECBPT field in
                  FCBSECT points to IHADECB.

IHADECB Control Block Content | Top of page

     IHADECB DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      IHADECB        DATA EVENT CONTROL BLOCKS FOR
    0000    0 Signed       4 DECSDECB       - EVENT CONTROL BLOCK
    0004    4 Signed       2 DECTYPE        - TYPE OF I/O REQUEST
              1... ....      DECBRD         X'80' DECBRD - READ SF
              ..1. ....      DECBWR         X'20' DECBWR - WRITE SF
    0006    6 Signed       2 DECLNGTH       - LENGTH OF KEY & DATA
    0008    8 Address      4 DECDCBAD       - V(DATA CONTROL BLOCK)
    000C   12 Address      4 DECAREA        - V(KEY & DATA, BUFFER)
    0010   16 Address      4 DECIOBPT       - V(IOB) BDAM EXTENSION
    0014   20 Address      4 DECKYADR       - V(KEY)
    0018   24 Address      4 DECRECPT       - V(BLOCK REFERENCE FIELD)
            SOME FREQUENTLY USED EQUATES
              00000020       DDNAM          FCBDSTYP - FILETYPE = DATA SET
                                            NAME
              ...1 ....      BLK            X'10' - RECFM=BLOCKED RECORDS
              ..1. ....      BS             X'20' - MACRF=BSAM
              ..1. ....      DA             X'20' - DSORG=DIRECT ACCESS
              1... ....      FXD            X'80' - RECFM=FIXED LENGTH
                                            RECORDS
              1... ....      IS             X'80' - DSORG=INDEXED SEQUENTIAL
              .... 1...      LOC            X'08' - MACRF=LOCATE MODE
              ...1 ....      MOV            X'10' - MACRF=MOVE MODE
              .1.. ....      PS             X'40' - DSORG=PHYSICAL SEQUENTIAL
              .... ..11      POU            X'03' - DSORG=PARTITIONED
                                            UNMOVEABLE
              .... ..1.      PO             X'02' - DSORG=PARTIONED
                                            ORGANIZATION
              1... ....      PREVIOUS       X'80' - OFLGS=PREVIOUS I/O
                                            OPERATION
              .1.. ....      QS             X'40' - MACRF=QSAM
              11.. ....      UND            X'C0' - RECFM=UNDEFIN FORMAT
                                            RECORDS
              .1.. ....      VAR            X'40' - RECFM=VARIABLE LENGTH
                                            RECORDS
              ..1. ....      ANSID          X'20' - RECFM=VARIABLE LENGTH
                                            RECS (ANSI)
              .... 1...      SPANNED        X'08' - RECFM=SPANNED

IHADECB Storage Layout | Top of page

    *** IHADECB - DATA EVENT CONTROL BLOCKS FOR
    *
    *     +---------------------------+-------------+-------------+
    *   0 |         DECSDECB          |  DECTYPE    |  DECLNGTH   |
    *     +---------------------------+-------------+-------------+
    *   8 |         DECDCBAD          |         DECAREA           |
    *     +---------------------------+---------------------------+
    *  10 |         DECIOBPT          |         DECKYADR          |
    *     +---------------------------+---------------------------+
    *  18 |         DECRECPT          | 1C
    *     +---------------------------+
    *
    *** IHADECB - DATA EVENT CONTROL BLOCKS FOR

IHADECB Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    ANSID          0018 20
    BLK            0018 10
    BS             0018 20
    DA             0018 20
    DDNAM          0018 00000020
    DECAREA        000C
    DECBRD         0004 80
    DECBWR         0004 20
    DECDCBAD       0008
    DECIOBPT       0010
    DECKYADR       0014
    DECLNGTH       0006
    DECRECPT       0018
    DECSDECB       0000
    DECTYPE        0004
    FXD            0018 80
    IS             0018 80
    LOC            0018 08
    MOV            0018 10
    PO             0018 02
    POU            0018 03
    PREVIOUS       0018 80
    PS             0018 40
    QS             0018 40
    SPANNED        0018 08
    UND            0018 C0
    VAR            0018 40

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:36:08 EDT.
Copyright IBM Corporation, 1990, 2020