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
 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         Host logical address of next OFB.
0004    4 Address      4 OFBDRB         HL-address of chain of open DRBKs
0008    8 Address      4 OFBMLEBK       HL-address of MLEBK chain.
000C   12 Signed       4 OFBIOBUF       Host logical address of I/O
                                        buffer. Will be backed BELOW2G
                                        since 31-bit HRA IDAL lists will
                                        be used.
0010   16 Address      4 OFBvFSB        Virt Free Storage addr of FSBK
0014   20 Signed       4 *              Reserved for future IBM use
0018   24 Signed       2 OFBSIZE        Size of OFBK in bytes
001A   26 Bitstring    1 OFBFLAG1       Flags
          1... ....      OFBSEUDO       X'80' This is a Pseudo-OPEN OFBK
          ...1 ....      OFBUNIQE       X'10' Only 1 OPEN against this
                                        OFBK
001B   27 Bitstring    1 OFBFLAG2       Flags
          1... ....      OFBOUTPT       X'80' This is an output OFBK
          .... ...1      OFBDATA        X'01' OFBRBUFF must be written
001C   28 Address      4 OFBIOR         Host logical address of IORBK if
                                        any.
0020   32 Dbl-Word     8 OFBLOCK (3)    Lock for file I/O
0038   56 Signed       4 OFBUSER1       Reserved for non-IBM use
003C   60 Signed       4 OFBUSER2       Reserved for non-IBM use
0040   64 Bitstring   48 OFBFSB         Interesting FSBK pieces
0070  112 Dbl-Word     8 OFBPTRS (0)    Start of variable length data
                                        Pointers to DASD blocks
          00000070       OFBSIZEB       (*-OFBK+7)/8*8 Size in bytes
          0000000E       OFBSIZED       (*-OFBK+7)/8 Size in d-words
       This section is subscripted (0:FSB#LVL)
0070  112 Dbl-Word     8 OFBPTR (0)     Pointers to DASD blocks
0070  112 Signed       4 OFBBLOCK       Disk block number of block
0074  116 Signed       4 OFBSCRPT       Subscript to child pointer
0078  120 Address      4 OFBgBUFF       CP Virt Free Storage addr of blk
007C  124 Address      4 OFBvBUFF       CP Virt Free Storage addr of pg
                                        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.
0080  128 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 |         OFBMLEBK          |         OFBIOBUF          |
*     +---------------------------+---------------------------+
*  10 |         OFBVFSB           |///////////////////////////|
*     +-------------+------+------+---------------------------+
*  18 |  OFBSIZE    |:FLAG1|:FLAG2|          OFBIOR           |
*     +-------------+------+------+---------------------------+
*  20 |                                                       |
*     =                       OFBLOCK                         =
*     |                                                       |
*     +---------------------------+---------------------------+
*  38 |         OFBUSER1          |         OFBUSER2          |
*     +---------------------------+---------------------------+
*  40 |                                                       |
*     =                        OFBFSB                         =
*     |                                                       |
*     +-------------------------------------------------------+
*
*** OFBK - CP Open File Block
          
*** Overlay for OFBPTRS in OFBK
*
*     +---------------------------+---------------------------+
*  70 |         OFBBLOCK          |         OFBSCRPT          |
*     +---------------------------+---------------------------+
*  78 |         OFBGBUFF          |         OFBVBUFF          |
*     +---------------------------+---------------------------+
*  80
*
*** Overlay for OFBPTRS in OFBK

OFBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
OFBgBUFF       0078
OFBvBUFF       007C
OFBvFSB        0010
OFBBLOCK       0070
OFBDATA        001B 01
OFBDRB         0004
OFBFLAG1       001A
OFBFLAG2       001B
OFBFSB         0040
OFBFWD         0000
OFBIOBUF       000C
OFBIOR         001C
OFBLOCK        0020
OFBMLEBK       0008
OFBOUTPT       001B 80
OFBPTR         0070
OFBPTRL        0080 00000010
OFBPTRS        0070
OFBSCRPT       0074
OFBSEUDO       001A 80
OFBSIZE        0018
OFBSIZEB       0070 00000070
OFBSIZED       0070 0000000E
OFBUNIQE       001A 10
OFBUSER1       0038
OFBUSER2       003C