XLDBK Back to Index page
 
Prolog 
Control Block Contents 
   XLDBK DSECT
   XLDENTRY DSECT
Storage Layout 
Cross Reference (Contains links to field and bit definitions)
Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.


  XLDBK Prolog Top of page
 
 NAME       : HCPXLDBK
 DESCRIPTION: eXtent List Definition BlocK.
 DSECT      : XLDBK
 FUNCTION   : The XLDBK is used for parameter passing for
              diagnose X'244'.
 LOCATED BY : Rx      - Diagnose X'244' Rx register.
 CREATED BY : Created in the guest virtual machine's storage and
              copied into a buffer page for CP use.
 DELETED BY : Deleted by the guest virtual machine.
 SERIALIZED : Guest Virtual Machine is responsible.
 RELOCATION CONSIDERATIONS : None
 COMMENTS   : This is a variable size block.
              Use the following formula to figure out the actual
              size of the control block.
              XLDSIZE+(((nnn(XLDENTSZ))+7)/8)= number of doublewords
              Where: XLDSIZE  - Header size in doublewords.
              nnn      - Number of contiguous extent entries.
              XLDENTSZ - Total size in bytes of one extent
              entry.
 
 
  XLDBK Control Block Content Top of page
 

 XLDBK DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure XLDBK eXtent List Definition BlocK. 0000 0 Signed 4 XLDALET ALET specifying the ad- dress space in which the next XLDBK resides. 0004 4 Signed 4 XLDFWDPT Forward pointer to next XLDBK. 0008 8 Signed 4 XLDENTCT Count of entries to be processed. 000C 12 Signed 4 XLDRSVD Reserved for IBM use. This field must contain zeroes. 0010 16 Signed 4 XLDENTR1 (0) Use XLDENTRY to map the entries that follow. The following are used to determine the size of the header for this control block. . 00000010 XLDLEN *-XLDBK Length of the header in bytes. 00000002 XLDSIZE (XLDLEN+7)/8 Size of the header in doublewords. The following DSECT represents an extent entry.
 XLDENTRY DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure XLDENTRY eXtent List Definition BlocK. 0000 0 Signed 4 XLDPRBN This is the pool- relative block number assigned to the block specified for XLDMRBN. 0004 4 Signed 4 XLDMRBN Relative-block number of record on minidisk. Referenced from the start of the virtual minidisk starting with zero (0). 0008 8 Signed 4 XLDCOUNT Number of relative- block numbers(RBNs) for this extent. 000C 12 Signed 2 XLDDEVNM Virtual device number of device to be mapped. 000E 14 Signed 2 * Reserved for IBM use. 00000010 XLDETLEN *-XLDENTRY Length of the 1st entry. 00000002 XLDESIZE (XLDETLEN+7)/8 Size of this control block in doublewords. 0010 16 Signed 4 XLDNXTET (0) Next extent in list. 00000100 XLDNMETP 4096/XLDETLEN The number of entries contained in a page. 00001000 XLDSZETP XLDETLEN*XLDNMETP Total storage size of all entries that can fit into a page.
 
 
  XLDBK Storage Layout Top of page
 
          
*** XLDBK - eXtent List Definition BlocK.
*
*     +---------------------------+---------------------------+
*   0 |         XLDALET           |         XLDFWDPT          |
*     +---------------------------+---------------------------+
*   8 |         XLDENTCT          |         XLDRSVD           |
*     +---------------------------+---------------------------+
*
*** XLDBK - eXtent List Definition BlocK.
          
*** XLDENTRY - eXtent List Definition BlocK.
*
*     +---------------------------+---------------------------+
*   0 |         XLDPRBN           |         XLDMRBN           |
*     +---------------------------+-------------+-------------+
*   8 |         XLDCOUNT          |  XLDDEVNM   |/////////////|
*     +---------------------------+-------------+-------------+
*
*** XLDENTRY - eXtent List Definition BlocK.
 
 
  XLDBK Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
XLDALET        0000
XLDCOUNT       0008
XLDDEVNM       000C
XLDENTCT       0008
XLDENTR1       0010
XLDESIZE       000E 00000002
XLDETLEN       000E 00000010
XLDFWDPT       0004
XLDLEN         0010 00000010
XLDMRBN        0004
XLDNMETP       0010 00000100
XLDNXTET       0010
XLDPRBN        0000
XLDRSVD        000C
XLDSIZE        0010 00000002
XLDSZETP       0010 00001000
 
This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:31:52 EDT.
Copyright IBM Corporation, 1990, 2020