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 (45)  This area reserved for the IORBK.
0168  360 Dbl-Word     8 PAGEXPBK (23)  This area reserved for the EXPBK.
     The area below is used for the Set Paging CCW data.
0220  544 Bitstring   16 PAGSPPAR (0)   This area contains the cache CCW
                                        data information.
0220  544 Bitstring   10 PAGDATA (0)    This is the data area for the Set
                                        Paging Parameter CCW.
0220  544 Bitstring    1 *
0221  545 Bitstring    9 PAGDATA1 (0)   Defined for the clear move
                                        instruction. ....
0221  545 Bitstring    5 *
0226  550 Bitstring    4 PAGCCHH        The cylinder/head info.
022A  554 Bitstring    6 *              Reserved for IBM use
     Redefinition of set paging parameter data area for ECKD and FBA paging
     devices.
0220  544 Bitstring   16 PAGDXDA        Define extent data area mapped by
                                        DXDA (ECKD) or DFDA (FBA)
          00000230       PAGCKSIZ       *-PAGBK Actual block size in
                                        bytes
          00000046       PAGSIZE        (((*-PAGBK)+7)/8) PAGBK siz in
                                        DWs (leave room for expansion)
          00000230       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                        =
*     |                                                       |
*     +-------------------------------------------------------+
* 168 |                                                       |
*     =                       PAGEXPBK                        =
*     |                                                       |
*     +------+----------------------------------+-------------+
* 220 |//////|//////////////////////////////////|  PAGCCHH-   |
*     +------+------+---------------------------+-------------+
* 228 |   -(226)    |/////////////////////////////////////////|
*     +-------------+-----------------------------------------+
* 230
*
*** PAGBK - Page I/O DSECT Block
          
*** Overlay for PAGSPPAR in PAGBK
*
*     +-------------------------------------------------------+
* 220 |                       PAGDXDA                         |
*     |                                                       |
*     +-------------------------------------------------------+
* 230
*
*** Overlay for PAGSPPAR in PAGBK

PAGBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
PAGBSIZE       0220 00000230
PAGCCHH        0226
PAGCKSIZ       0220 00000230
PAGDATA        0220
PAGDATA1       0221
PAGDXDA        0220
PAGEXPBK       0168
PAGIORBK       0000
PAGSIZE        0220 00000046
PAGSPPAR       0220