XBLBK

Prolog  

Control Block Contents  
   XBLBK DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

XBLBK Prolog

 NAME       : HCPXBLBK
 DESCRIPTION: XA buffer list block.
 DSECT      : XBLBK
 FUNCTION   : This block is used to keep track of the real buffers
              that contain virtual device information.
 LOCATED BY : Addressability is established when obtaining
              FREE storage. The block is not anchored anywhere.
 CREATED BY : HCPIIR when saving the virtual device information.
              - HCPNSE when restoring the virtual device information.
 DELETED BY : HCPNSE will return the block to FREE storage.
 RELOCATION CONSIDERATIONS : None
 COMMENTS   : This is a variable length block. The size is the header,
              plus one-half the number of real page buffers, plus one.

XBLBK Control Block Content

XBLBK DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      XBLBK          XA buffer list block.
0000    0 Bitstring    8 *              Reserved for future IBM use.
0008    8 Signed       4 XBLDEVCT       COUNT OF THE NUMBER OF DEVICES.
000C   12 Signed       4 XBLRBFCT       COUNT OF REAL BUFFER ADDRESSES.
          00000002       XBLHDRSZ       (((*-XBLBK)+7)/8) This is the
                                        header size in DW.
0010   16 Signed       4 XBLDATA (0)    Start of variable length data.
0010   16 Signed       4 XBLRBFAD       The first real buffer address
                                        starts here.
          00000004       XBLRBSIZ       (*-XBLRBFAD) This is the size of
                                        an entry for a real buffer.

XBLBK Storage Layout

          
*** XBLBK - XA buffer list block.
*
*     +-------------------------------------------------------+
*   0 |///////////////////////////////////////////////////////|
*     +---------------------------+---------------------------+
*   8 |         XBLDEVCT          |         XBLRBFCT          |
*     +---------------------------+---------------------------+
*
*** XBLBK - XA buffer list block.
          
*** Overlay for XBLDATA in XBLBK
*
*     +---------------------------+
*  10 |         XBLRBFAD          | 14
*     +---------------------------+
*
*** Overlay for XBLDATA in XBLBK

XBLBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
XBLDATA        0010
XBLDEVCT       0008
XBLHDRSZ       000C 00000002
XBLRBFAD       0010
XBLRBFCT       000C
XBLRBSIZ       0010 00000004