Programming Interface Information: This page documents intended Programming Interfaces that allow the customer to write programs to obtain the services of z/VM.

#### SCBLOCK

Prolog

Control Block Contents
SCBLOCK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### SCBLOCK Prolog

     Name       : SCBLOCK
     Description: Subcommand Control Block
     DSECT      : SCBLOCK
     Function   : The SCBLOCK describes the dynamic
                  entry point for the SUBCOM function and is
                  dynamically allocated from free storage by
                  DMSITS.

#### SCBLOCK Control Block Content

#### SCBLOCK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      SCBLOCK        Subcommand Control Block
    0000    0 Signed       4 SCBFWPTR       CHAIN POINTER TO NEXT SCBLOCK
    0004    4 Address      4 SCBWKWRD       AVAILABLE FOR USER INFORMATION
    0008    8 Character    8 SCBNAME        NAME OF SUBCOMMAND ENVIRONMENT
    0010   16 Dbl-Word     8 SCBPSW (0)     STARTING PSW FOR SUBCOMMAND
    0010   16 Bitstring    1 SCBINT         PSW INTERRUPT BITS
          The following table shows the combination of bits
          in SCBPSW that determine what the various INTTYPEs are.
     INTTYPE             |BIT 0|BIT 1|    |BIT 7|HEX value
     --------------------------------------------------------
     NONE                   0     0        0     00
     EXTERNAL               0     0        1     01
     NONCONSOLE             0     1        0     40
     NONCONSOLE & EXTERNAL  0     1        1     41
     CONSOLE                1     0        0     80
     CONSOLE & EXTERNAL     1     0        1     81
     IO                     1     1        0     C0
     ALL                    1     1        1     C1
                 NUCX FIELDS.  THESE ARE PRESENT, BUT NOT USED,
                 IN SCBLOCKS ON THE NUCSCBLK CHAIN.
    0011   17 Bitstring    1 SCBKEY         PSW KEY
    0012   18 Bitstring    1 SCBSFLAG       SYSTEM FLAG BYTE.
              1... ....      SCBSFSYS       X'80' DENOTES "SYSTEM" ROUTINE --
                                            WILL NOT BE AUTOMATICALLY DELETED
                                            DURING ABEND PROCESSING.
              .1.. ....      SCBSFSER       X'40' DENOTES "SERVICE" ROUTINE
                                            -- WILL BE CALLED WITH "PURGE"
                                            ARGUMENT DURING ABEND PROCESSING.
              ..1. ....      SCBSFABN       X'20' USED DURING ABEND
                                            PROCESSING.
              ...1 ....      SCBSFEND       X'10' DENOTES 'END OF COMMAND'
                                            ROUTINE
              ..1. ....      SCBSFINT       SCBSFABN USED DURING END OF
                                            COMMAND PROCESSING.
              .... 1...      SCBSPERM       X'08' DENOTES THAT THIS NUCLEUS
                                            EXTENSION WON'T BE DELETED DURING
                                            NUCXDROP ALL PROCESS
              .... .1..      SCBSFIMM       X'04' DENOTES THAT THIS NUCLEUS
                                            EXTENSION CAN ALSO BE CALLED AS
                                            AN IMMEDIATE COMMAND
              .... ..1.      SCBSFX         X'02' DENOTES A LOOK-ASIDE ENTRY
                                            POINTING TO A REAL CMS NUCLEUS
                                            ROUTINE.
              .... ...1      SCBSHIDE       X'01' USED TO HIDE A NUCLEUS
                                            EXTENSION TEMPORARILY.
    0013   19 Bitstring    1 SCBUFLAG       USER FLAG BYTE.
    0014   20 Address      4 SCBENTR        ENTRY POINT ADDRESS IN PSW
    0018   24 Address      4 SCBXORG        ADDRESS WHERE NUCLEUS EXTENSION
                                            WAS LOADED IN FREE STORAGE.
    001C   28 Signed       4 SCBXLEN        LENGTH IN BYTES OF NUCLEUS
                                            EXTENSION. MAY BE ZERO FOR
                                            SECONDARY ENTRY POINTS.
    0020   32 Bitstring    1 SCBSFLG2       F*2 SECOND FLAG BYTE
              1... ....      SCBSFA31       X'80' EXTENSION IS AMODE 31
              .1.. ....      SCBSFA24       X'40' EXTENSION IS AMODE 24
              ..1. ....      SCBSFSEG       X'20' SEGMENT RESIDENT WHEN BOTH
                                            ON, EXTENSION IS AMODE ANY, WHEN
                                            BOTH OFF, EXTENSION IS AMODE
                                            SAME.
              ...1 ....      SCBSFUNC       X'10' Indicate function can not
                                            be S5U29592 invoked from the
                                            command line
              .... 1...      SCBSMT         X'08' mt subcom
              .... .1..      SCBSTPRV       X'04' thread private subcom
    0021   33 Bitstring    1 * (3)          RESERVED FOR FURTURE USE
    0024   36 Character    8 SCBSEGID       LOGICAL SEGMENT IDENTIFIER
    002C   44 Signed       4 SCBTESTK       thread execomm stack
    0030   48 Dbl-Word     8 * (0)          KEEP DOUBLEWORD ALIGNED
              00000030       SCBLOCKB       *-SCBLOCK LENGTH IN BYTES
              00000006       SCBLOCKD       (SCBLOCKB+7)/8 LENGTH IN DWORD

#### SCBLOCK Storage Layout

    *** SCBLOCK - Subcommand Control Block
    *
    *     +---------------------------+---------------------------+
    *   0 |         SCBFWPTR          |         SCBWKWRD          |
    *     +---------------------------+---------------------------+
    *   8 |                       SCBNAME                         |
    *     +------+------+------+------+---------------------------+
    *  10 |SCBINT|SCBKEY|:SFLAG|:UFLAG|         SCBENTR           |
    *     +------+------+------+------+---------------------------+
    *  18 |         SCBXORG           |         SCBXLEN           |
    *     +------+--------------------+---------------------------+
    *  20 |:SFLG2|////////////////////|        SCBSEGID-          |
    *     +------+--------------------+---------------------------+
    *  28 |          -(024)           |         SCBTESTK          |
    *     +---------------------------+---------------------------+
    *  30
    *
    *** SCBLOCK - Subcommand Control Block

#### SCBLOCK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    SCBENTR        0014
    SCBFWPTR       0000
    SCBINT         0010
    SCBKEY         0011
    SCBLOCKB       0030 00000030
    SCBLOCKD       0030 00000006
    SCBNAME        0008
    SCBPSW         0010
    SCBSEGID       0024
    SCBSFABN       0012 20
    SCBSFA24       0020 40
    SCBSFA31       0020 80
    SCBSFEND       0012 10
    SCBSFIMM       0012 04
    SCBSFINT       0012 20
    SCBSFLAG       0012
    SCBSFLG2       0020
    SCBSFSEG       0020 20
    SCBSFSER       0012 40
    SCBSFSYS       0012 80
    SCBSFUNC       0020 10
    SCBSFX         0012 02
    SCBSHIDE       0012 01
    SCBSMT         0020 08
    SCBSPERM       0012 08
    SCBSTPRV       0020 04
    SCBTESTK       002C
    SCBUFLAG       0013
    SCBWKWRD       0004
    SCBXLEN        001C
    SCBXORG        0018

This information is based on z/VM V5R2.0.
Last updated on 6 Dec 2005 at 15:43:57 EDT.
Copyright IBM Corporation, 1990, 2005