Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

#### RTHBK

Prolog

Control Block Contents
RTHBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### RTHBK Prolog

     NAME       : HCPRTHBK
     DESCRIPTION: RECORDING TABLE HEADER BLOCK
     DSECT      : RTHBK
     FUNCTION   : MAPS OUT THE HEADER INFORMATION ON THE RECORDING
                  SYSTEM SERVICE TABLE
     LOCATED BY : SYSRECQU
     SERIALIZED : SYSRECLK
     NOTES      : This control block gets checkpointed during SHUTDOWN and
                  will be read back in during a WARM start.  Therefore, if
                  the format of the block changes due to service being
                  applied before the warm start, code should be in place to
                  distinguish between the old and new format.  (See the
                  note below describing the RTHVERS field.)

#### RTHBK Control Block Content

#### RTHBK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      RTHBK          RECORDING TABLE HEADER BLOCK
    0000    0 Signed       4 RTHQUE         ADDRESS OF THE FIRST SYSTEM
                                            RECORD ON THE RECORDING QUEUE.
    0004    4 Signed       2 *              RESERVED
    0006    6 Signed       2 *              RESERVED. Previously: RTHMSGN
                                            field
          NOTES      : The following field is used to indicate when the RTHBK
                format has changed and what that change was due to.
                Any code defined here should be checked in HCPRECKP
                when old format RTHBK is read from the checkpoint
                cylinders. The old format RTHBK should then be updated
                appropriately to the new format. Code should also be
                added to HCPRIURI to set the code for the RTHBK
                that is being newly created AFTER the format change.
                A new code should only need to be defined
                here when a change to the RTHBK causes it to be
                incompatible with a previous format. Due to
                compatibility, the displacement of the RTHVERS
                field should NEVER change.  Previous versions of this
                control block had this field marked 'RESERVED' and
                the field was known to be zero.  Therefore, previous
                versions were version X'00'.
    0008    8 Bitstring    1 RTHVERS        RTHBK Version indicator
              00000000       RTHVN00        X'00' For version 00, original
                                            format
              00000001       RTHVN01        X'01' For version 01, Full Page
                                            RTHBK
    0009    9 Bitstring    1 RTHRID         RECORDING TABLE IDENTIFIER. SET
                                            TO X'FF' AT INITIALIZATION TIME.
    000A   10 Signed       2 RTHFRESZ       RTHBK BLOCK SIZE IN DOUBLE WORDS
    000C   12 Bitstring    1 RTHFLAG        RECORDING TABLE FLAGS.
              1... ....      RTHRINIT       X'80' PURGE IN PROGRESS
              .1.. ....      RTHRINC        X'40' I/O COMPLETE IN PROGRESS
    000D   13 Bitstring    1 *              RESERVED
    000E   14 Signed       2 RTHDCNT        LENGTH OF RTHDATA IN BYTES.
                                            RTHDATA IS MAPPED OUT INTO
                                            INDIVIDUAL RECORDING TABLE
                                            ENTRIES WITH THE RECBK DSECT.
    0010   16 Character    1 RTHDATA (0)    FIRST RECBK ENTRY IN THE
                                            RECORDING TABLE.
                            COMMON EQUATES
                       OFFSET TO RECBK WORK AREA IN RECORDING TABLE.
              00000FB0       RTHRECWK       (100*RECBLEN)+(RTHDATA-RTHBK)
                                            OFFSET TO RSSBK WORK AREA IN
                                            RECORDING TABLE.
              00000FD8       RTHRSSWK       RTHRECWK+RECBLEN SIZE OF THE
                                            RTHBK (RECORDING TABLE) IN DOUBLE
                                            WORDS
              000001FE       RTHDWRDS       (RTHRSSWK+RSSBLEN+7)/8 SIZE OF
                                            RTHDATA IN BYTES.
              00000FE0       RTHDATAB       (RTHDWRDS*8)-(RTHDATA-RTHBK)

#### RTHBK Storage Layout

    *** RTHBK - RECORDING TABLE HEADER BLOCK
    *
    *     +---------------------------+-------------+-------------+
    *   0 |          RTHQUE           |/////////////|/////////////|
    *     +------+------+-------------+------+------+-------------+
    *   8 |:VERS |RTHRID|  RTHFRESZ   |:FLAG |//////|  RTHDCNT    |
    *     +------+------+-------------+------+------+-------------+
    *
    *** RTHBK - RECORDING TABLE HEADER BLOCK

#### RTHBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    RTHDATA        0010
    RTHDATAB       0010 00000FE0
    RTHDCNT        000E
    RTHDWRDS       0010 000001FE
    RTHFLAG        000C
    RTHFRESZ       000A
    RTHQUE         0000
    RTHRECWK       0010 00000FB0
    RTHRID         0009
    RTHRINC        000C 40
    RTHRINIT       000C 80
    RTHRSSWK       0010 00000FD8
    RTHVERS        0008
    RTHVN00        0008 00000000
    RTHVN01        0008 00000001

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 17:21:05 EDT.
Copyright IBM Corporation, 1990, 2005