Programming Interface Information: This information is NOT intended to be
used as Programming Interfaces of VM/ESA. It is to be used for diagnosis only.

EXPBK

Prolog  

Control Block Contents  

EXPBK DSECT

EXPQUENT DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

EXPBK Prolog

 NAME       : HCPEXPBK
 DESCRIPTION: EXPOSURE BLOCK
 DSECT      : EXPBK
 FUNCTION   : The exposure block contains necessary information
              about a CP volume for paging information.
 LOCATED BY : CPVEXPBK - For single exposure devices, points to
              the exposure block.
              For multiple exposure devices, points to
              the first one of a contiguous group.
 CREATED BY : HCPRDAAT - When the CP owned volume is brought on
              line at IPL time and during the ATTACH
              command processing.
 DELETED BY : HCPRDADT - When the CP owned volume is DETACHed from
              the system.
 SERIALIZED : EXPLCKFG - A Test and Set instruction is used to set
              the lock flag on to serialize this control
              block and the IORBK control block for the
              exposure.
 COMMENTS   :
              Each logical path to a device is an exposure.
              One device may have several exposures.  If so,
              each exposure has its own EXPBK, and all the EXPBKs
              for a single device are located in contiguous
              storage.

 

EXPBK Control Block Content


EXPBK DSECT

Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure EXPBK EXPOSURE BLOCK Flags for the exposure block. 0000 0 Signed 4 EXPFLAGS (0) Flags for the exposure block 0000 0 Bitstring 1 EXPLCKFG Exposure lock byte. X'FF' - Indicates this exposure is locked. X'00' - Indicates this exposure is available for use .... .... EXPLCKRL X'00' Used to release the exposure lock This flag is to keep the status information for this exposure. 0001 1 Bitstring 1 EXPSTATF Exposure status flag 00000000 EXPNOP X'00' Indicates that neither a RSCH or a SSCH is required. 00000001 EXPDQINP X'01' Indicates a DEQUEUE in progress 00000002 EXPRSCH X'02' Indicates that a RSCH is required 00000004 EXPSSCH X'04' Indicates that a SSCH is required 0002 2 Bitstring 1 EXPTYPEF Exposure type flag .... ..1. EXPFBA X'02' This is an FBA device .... ...1 EXPECKD X'01' Indicates this is an ECKD paging device 0003 3 Bitstring 1 * Reserved for future IBM use Maximum number of outstanding DASD I/O for multiple read or writes. 0004 4 Signed 2 EXPMAXMW Maximum number of multiple writes that can be added into the channel program. This value is 4 * number of records per track. 0006 6 Signed 2 EXPQCNEG Number of times EXPCURQC went neg. The IORBK for this exposure 0008 8 Address 4 EXPFACPA First Active Channel Program Addr 000C 12 Address 4 EXPSCCWP Suspended CCW package. This is also the address of the last PIOBK in the current channel program. These are deferred saveareas when all CCW packages are used for this exposure. The saveareas are a single threaded list with the last pointer equal to zero. 0010 16 Address 4 EXPSFDSV First deferred savearea for single reads and writes 0014 20 Address 4 EXPSCDSV Current deferred savearea that will be dequeue for single reads and write 0018 24 Address 4 EXPMRDFQ Queue anchor for deferred multiple read operations which are sorted in ascending order by cylinder number. The end of queue is zeroes 001C 28 Address 4 EXPMRCQ Address of the current deferred read SAVBK which is the current active cylinder number. 0020 32 Address 4 EXPMWDFQ Queue anchor for deferred multiple write operations which are sorted in ascending order by cylinder number. The end of queue is zeroes 0024 36 Address 4 EXPMWCQ Address of the current deferred write SAVBK which is the current active cylinder number. Monitor counters. 0028 40 Signed 4 EXPCTPRD Total count of page read operations for this device. Note that page read operations may be directed to devices without any cylinders specifically defined as type PAGE. 002C 44 Signed 4 EXPCTPWR Total count of page write operations for this device. Note that page write operations may be directed to devices without any cylinders specifically defined as type PAGE. 0030 48 Signed 4 EXPCTSRD Total count of spooling reads for this device. 0034 52 Signed 4 EXPCTSWR Total count of spooling writes for this device. 0038 56 Signed 4 EXPCTACP Total count of paging/spooling reads and writes added to an existing channel program without executing a SSCH or RSCH. 003C 60 Signed 4 EXPCURQC Cardinal count of all outstanding paging/spooling reads/writes for this device. 0040 64 Signed 4 EXP2BQED Count of slots that have been assigned on this CPVOL but have not yet been added to EXPCURQC (CPVOL because EXP2BQED is only valid in the first EXPBK for multi exposure devices). This count is updated using CS logic 0044 68 Address 4 EXPIORBK IORBK for this exposure. The IORBK is always at the beginning of each PAGBK so this field doubles as the PAGBK address 00000044 EXPPAGBK EXPIORBK,4 PAGBK for this exposure 0048 72 Signed 4 EXPCTUSI Total count of the number of times the channel program had to be terminated to allow user I/O. This is an indicator of interference between user and paging/spooling I/O. 004C 76 Signed 4 EXPDEVST Exposure service time. 0050 80 Signed 4 EXPMLOAD Exposure MLOAD. 0054 84 Signed 4 EXPTIMER Exposure timestamp for SSCH/RSCH. 0058 88 Signed 4 EXPINTIM Exposure timestamp at I/O interrupt time. .... 005C 92 Signed 4 EXPNMPIO Number of active PIOBKS at I/O interrupt time used to calc service time. 0060 96 Address 4 EXPRDCBK Address of the RDCBK. 0064 100 Signed 4 EXPCONT (20) Count of 20 contiguous free spaces allocated from 1 to 20 plus. 00B4 180 Signed 4 EXPBKEND (0) End of EXPBK. 000000B4 EXPBSIZE *-EXPBK Size of this DSECT in Bytes 00000017 EXPSIZE (((*-EXPBK)+7)/8) Size in double-words The next three statements EXPQUENT, EXPQANCH, and EXPQCURR are used to map the multiple read and write queue fields EXPMRDFQ, EXPMRCQ and EXPMWDFQ, EXPMWCQ.

EXPQUENT DSECT

Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure EXPQUENT EXPOSURE BLOCK 0000 0 Address 4 EXPQANCH Anchor for multiple defer queues. 0004 4 Address 4 EXPQCURR Current pointer to CPEBK in queue.

 

EXPBK Storage Layout

*** EXPBK - EXPOSURE BLOCK
*
*     +------+------+------+------+-------------+-------------+
*   0 |:LCKFG|:STATF|:TYPEF|//////|  EXPMAXMW   |  EXPQCNEG   |
*     +------+------+------+------+-------------+-------------+
*   8 |         EXPFACPA          |         EXPSCCWP          |
*     +---------------------------+---------------------------+
*  10 |         EXPSFDSV          |         EXPSCDSV          |
*     +---------------------------+---------------------------+
*  18 |         EXPMRDFQ          |         EXPMRCQ           |
*     +---------------------------+---------------------------+
*  20 |         EXPMWDFQ          |         EXPMWCQ           |
*     +---------------------------+---------------------------+
*  28 |         EXPCTPRD          |         EXPCTPWR          |
*     +---------------------------+---------------------------+
*  30 |         EXPCTSRD          |         EXPCTSWR          |
*     +---------------------------+---------------------------+
*  38 |         EXPCTACP          |         EXPCURQC          |
*     +---------------------------+---------------------------+
*  40 |         EXP2BQED          |         EXPIORBK          |
*     +---------------------------+---------------------------+
*  48 |         EXPCTUSI          |         EXPDEVST          |
*     +---------------------------+---------------------------+
*  50 |         EXPMLOAD          |         EXPTIMER          |
*     +---------------------------+---------------------------+
*  58 |         EXPINTIM          |         EXPNMPIO          |
*     +---------------------------+---------------------------+
*  60 |         EXPRDCBK          |                           |
*     +---------------------------+                           |
*  68 |                                                       |
*     =                       EXPCONT                         =
*     |                           +---------------------------+
*     |                           |                           |
*     +---------------------------+                           |
*  B8 |                                                       |
*     =                       EXPBKEND                        =
*     |                                                       |
*     +-------------------------------------------------------+
*
*** EXPBK - EXPOSURE BLOCK
*** EXPQUENT - EXPOSURE BLOCK
*
*     +---------------------------+---------------------------+
*   0 |         EXPQANCH          |         EXPQCURR          |
*     +---------------------------+---------------------------+
*   8
*
*** EXPQUENT - EXPOSURE BLOCK

 

EXPBK Cross Reference

(contains links to field and bit definitions)
Symbol         Dspl Value
-------------- ---- -----

EXPBKEND 00B4

EXPBSIZE 00B4 000000B4

EXPCONT 0064

EXPCTACP 0038

EXPCTPRD 0028

EXPCTPWR 002C

EXPCTSRD 0030

EXPCTSWR 0034

EXPCTUSI 0048

EXPCURQC 003C

EXPDEVST 004C

EXPDQINP 0001 00000001

EXPECKD 0002 01

EXPFACPA 0008

EXPFBA 0002 02

EXPFLAGS 0000

EXPINTIM 0058

EXPIORBK 0044

EXPLCKFG 0000

EXPLCKRL 0000 00

EXPMAXMW 0004

EXPMLOAD 0050

EXPMRCQ 001C

EXPMRDFQ 0018

EXPMWCQ 0024

EXPMWDFQ 0020

EXPNMPIO 005C

EXPNOP 0001 00000000

EXPPAGBK 0044 00000044

EXPQANCH 0000

EXPQCNEG 0006

EXPQCURR 0004

EXPRDCBK 0060

EXPRSCH 0001 00000002

EXPSCCWP 000C

EXPSCDSV 0014

EXPSFDSV 0010

EXPSIZE 00B4 00000017

EXPSSCH 0001 00000004

EXPSTATF 0001

EXPTIMER 0054

EXPTYPEF 0002

EXP2BQED 0040


This information is based on VM/ESA 2.4.0.
Last updated on 3 Aug 1999 at 12:18:56 EDT.
Copyright IBM Corporation, 1990, 1999