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Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
EXPBK
Control Block Contents
EXPBK DSECT
EXPQUENT DSECT
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 =
* | +---------------------------+
* | |
* +---------------------------+
*
*** EXPBK - EXPOSURE BLOCK
*** EXPQUENT - EXPOSURE BLOCK
*
* +---------------------------+---------------------------+
* 0 | EXPQANCH | EXPQCURR |
* +---------------------------+---------------------------+
* 8
*
*** EXPQUENT - EXPOSURE BLOCK
EXPBK Cross Reference
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 z/VM V4R2.0.
Last updated on 17 Oct 2001 at 15:50:01 EDT.
Copyright IBM Corporation, 1990, 2001