IBM: OFBK

Programming Interface Information: This information is NOT intended to be
used as Programming Interfaces of VM/ESA. It is to be used for diagnosis only.

OFBK

Prolog

Control Block Contents

OFBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

OFBK Prolog

 Name       : HCPOFBK
 Description: CP Open File Block
 STATUS     : VM/ESA Version 2, Release 1.0
 DSECT      : OFBK
 Function   : The OFBK contains information about each
              open CMS file on CP accessed minidisks
 Located by : ACSBK.ACSOFB
              OFBK.OFBFWD
              DRBK.DRBOFB
 Created by : HCPZIA
              HCPZIO
 Deleted by : HCPZIC
              HCPZIR

OFBK Control Block Content


OFBK DSECT
Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      OFBK           CP Open File Block
0000    0 Address      4 OFBFWD         A( next OFB )
0004    4 Address      4 OFBDRB         A( chain of open DRBKs )
0008    8 Address      4 OFBRFSB        R-addr of FSB
000C   12 Address      4 OFBVFSB        V-addr of FSB
0010   16 Address      4 OFBMLEBK       Address of MLEBK chain
0014   20 Signed       4 *              Reserved for future IBM use
0018   24 Signed       4 *              Reserved for future IBM use
001C   28 Signed       4 *              Reserved for future IBM use
0020   32 Signed       2 OFBSIZE        Size of OFBK in bytes
0022   34 Bitstring    1 OFBFLAG1       Flags
          1... ....      OFBSEUDO       X'80' This is a Pseudo-OPEN OFBK
                                        EQU X'40' EQU X'20'
          ...1 ....      OFBUNIQE       X'10' Only 1 OPEN against this
                                        OFBK EQU X'08' EQU X'04' EQU
                                        X'02' EQU X'01'
0023   35 Bitstring    1 OFBFLAG2       Flags
          1... ....      OFBOUTPT       X'80' This is an output OFBK EQU
                                        X'40' EQU X'20' EQU X'10' EQU
                                        X'08' EQU X'04' EQU X'02'
          .... ...1      OFBDATA        X'01' OFBRBUFF must be written
0024   36 Address      4 OFBIOR         A( IORBK, if any )
0028   40 Dbl-Word     8 OFBLOCK (3)    Lock for file I/O
0040   64 Signed       4 OFBUSER1       Reserved for non-IBM use
0044   68 Signed       4 OFBUSER2       Reserved for non-IBM use
0048   72 Dbl-Word     8 OFBPTRS (0)    Start of variable length data
                                        Pointers to DASD blocks
          00000048       OFBSIZEB       (*-OFBK+7)/8*8 Size in bytes
          00000009       OFBSIZED       (*-OFBK+7)/8 Size in d-words
     This section is subscripted (0:FSB#LVL)
0048   72 Dbl-Word     8 OFBPTR (0)     Pointers to DASD blocks
0048   72 Signed       4 OFBBLOCK       Disk block number of block
004C   76 Signed       4 OFBSCRPT       Subscript to child pointer
0050   80 Address      4 OFBRBUFF       R-addr of block
0054   84 Address      4 OFBVBUFF       V-addr of block When we page-in
                                        and lock these file I/O buffers,
                                        this address will have its high
                                        order bit turned on. This
                                        technique is used principally to
                                        detect the condition where some
                                        of these buffers were properly
                                        paged-in and locked but another
                                        failed due to a paging error.
                                        Only those buffers that have this
                                        bit on will be unlocked.
0058   88 Dbl-Word     8 * (0)          Round up to d-word boundary
          00000010       OFBPTRL        *-OFBPTR Length of these fields

OFBK Storage Layout

*** OFBK - CP Open File Block
*
*     +---------------------------+---------------------------+
*   0 |          OFBFWD           |          OFBDRB           |
*     +---------------------------+---------------------------+
*   8 |         OFBRFSB           |         OFBVFSB           |
*     +---------------------------+---------------------------+
*  10 |         OFBMLEBK          |///////////////////////////|
*     +---------------------------+---------------------------+
*  18 |///////////////////////////|///////////////////////////|
*     +-------------+------+------+---------------------------+
*  20 |  OFBSIZE    |:FLAG1|:FLAG2|          OFBIOR           |
*     +-------------+------+------+---------------------------+
*  28 |                                                       |
*     =                       OFBLOCK                         =
*     |                                                       |
*     +---------------------------+---------------------------+
*  40 |         OFBUSER1          |         OFBUSER2          |
*     +---------------------------+---------------------------+
*  48 |                                                       |
*     =                       OFBPTRS                         =
*     |                                                       |
*     +-------------------------------------------------------+
*
*** OFBK - CP Open File Block
*** Overlay for OFBPTRS in OFBK
*
*     +---------------------------+---------------------------+
*  48 |         OFBBLOCK          |         OFBSCRPT          |
*     +---------------------------+---------------------------+
*  50 |         OFBRBUFF          |         OFBVBUFF          |
*     +---------------------------+---------------------------+
*  58
*
*** Overlay for OFBPTRS in OFBK