IBM: SCBLOCK

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

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
          00000020       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