PAGBK

Prolog  

Control Block Contents  
   PAGBK DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

PAGBK Prolog

 NAME       : HCPPAGBK
 DESCRIPTION: Page I/O DSECT Block
 DSECT      : PAGBK
 FUNCTION   : PAGBK maps a 512 byte aligned free storage
              block that contains the IORBK, EXPBK (for single
              exposures), and the Set Paging Parameter CCW or
              the Define Extent Data Area.
 LOCATED BY : EXPIORBK - Field in the exposure block that points
              to the beginning of the block.
 NOTES      : To use this dsect the following dsects must also
              be included in the module. HCPIORBK, HCPEXPBK.

PAGBK Control Block Content

PAGBK DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      PAGBK          Page I/O DSECT Block
     Beginning of the IORBK for this exposure.
0000    0 Dbl-Word     8 PAGIORBK (57)  This area reserved for the IORBK.
01C8  456 Dbl-Word     8 PAGEXPBK (23)  This area reserved for the EXPBK.
     The area below is used for the Set Paging CCW data.
0280  640 Bitstring   16 PAGSPPAR (0)   This area contains the cache CCW
                                        data information.
0280  640 Bitstring   10 PAGDATA (0)    This is the data area for the Set
                                        Paging Parameter CCW.
0280  640 Bitstring    1 *
0281  641 Bitstring    9 PAGDATA1 (0)   Defined for the clear move
                                        instruction.
0281  641 Bitstring    5 *
0286  646 Bitstring    4 PAGCCHH        The cylinder/head info.
028A  650 Bitstring    6 *              Reserved for IBM use
     Redefinition of set paging parameter data area for ECKD and FBA paging
     devices.
0280  640 Bitstring   16 PAGDXDA        Define extent data area mapped by
                                        DXDA (ECKD) or DFDA (FBA)
          00000290       PAGCKSIZ       *-PAGBK Actual block size in
                                        bytes
          00000052       PAGSIZE        (((*-PAGBK)+7)/8) PAGBK siz in
                                        DWs (leave room for expansion)
          00000290       PAGBSIZE       *-PAGBK Non theoretical PAGBK
                                        size in bytes (leave room for
                                        expansion)
     CKMAINT PAGCKSIZ,GT,512 Check block size

PAGBK Storage Layout

          
*** PAGBK - Page I/O DSECT Block
*
*     +-------------------------------------------------------+
*   0 |                                                       |
*     =                       PAGIORBK                        =
*     |                                                       |
*     +-------------------------------------------------------+
* 1C8 |                                                       |
*     =                       PAGEXPBK                        =
*     |                                                       |
*     +------+----------------------------------+-------------+
* 280 |//////|//////////////////////////////////|  PAGCCHH-   |
*     +------+------+---------------------------+-------------+
* 288 |   -(286)    |/////////////////////////////////////////|
*     +-------------+-----------------------------------------+
* 290
*
*** PAGBK - Page I/O DSECT Block
          
*** Overlay for PAGSPPAR in PAGBK
*
*     +-------------------------------------------------------+
* 280 |                       PAGDXDA                         |
*     |                                                       |
*     +-------------------------------------------------------+
* 290
*
*** Overlay for PAGSPPAR in PAGBK

PAGBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
PAGBSIZE       0280 00000290
PAGCCHH        0286
PAGCKSIZ       0280 00000290
PAGDATA        0280
PAGDATA1       0281
PAGDXDA        0280
PAGEXPBK       01C8
PAGIORBK       0000
PAGSIZE        0280 00000052
PAGSPPAR       0280