Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.

PGS64

Prolog  

Control Block Contents  
   PGS64 DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  


 

PGS64 Control Block Content


PGS64 DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      PGS64          PAGE STATUS TABLE ENTRY
0000    0 Dbl-Word     8 PGSGENTR       Virtual Page Status Entry
0000    0 Signed       4 PGS64W0        Mirror of ESA/390 PGSTE
0004    4 Signed       4 PGS64W1        Reserved for IBM use
          00000008       PGSGLENT       *-PGSGENTR Length of one Status
                                        Table Entry
0008    8 Signed       4 PGSGNEXT (0)   Next Page Status Table Entry
0000    0 Bitstring    1 PGSGVKEY       Guest Storage key bits 0-4
          1111 ....      PGSVKACC       X'F0' Access-control key value
          .... 1...      PGSVKFET       X'08' Fetch-protection control
          1111 1...      PGSVKACF       PGSVKACC+PGSVKFET Acc-ctrl &
                                        fetch-prot bits
0001    1 Bitstring    1 PGSGRCP        Architected area for RCP byte if
                                        storage key assist is being
                                        utilized, or the page belongs to
                                        the system.
          1... ....      PGSPCL         X'80' Page Control Lock
          .1.. ....      PGSRCPHR       X'40' Host backup reference bit
                                        used for system pages
          ..1. ....      PGSRCPHC       X'20' Host backup change bit used
                                        for system pages
          .11. ....      PGSHOST        PGSRCPHR+PGSRCPHC Mask for host
                                        bits
          .... .1..      PGSGREF        X'04' Guest backup reference bit
          .... ..1.      PGSGCH         X'02' Guest backup change bit
          .... .11.      PGSGUEST       PGSGREF+PGSGCH Mask for guest
                                        bits
          1... ....      RCPLOCK        X'80' RCP LOCK HELD
          .1.. ....      RCPHREF        X'40' HOST BACKUP REFERENCE BIT
          ..1. ....      RCPHCH         X'20' HOST BACKUP CHANGE BIT
          .11. ....      RCPHOST        RCPHREF+RCPHCH MASK FOR HOST BITS
          .... .1..      RCPGREF        X'04' GUEST BACKUP REFERENCE BIT
          .... ..1.      RCPGCH         X'02' GUEST BACKUP CHANGE BIT
          .... .11.      RCPGUEST       RCPGREF+RCPGCH MASK FOR GUEST
                                        BITS
     PGSPCL is used for page serialization. This bit (and therefore page
     serialization) may only be obtained through the use of the page
     serialization macros.
     Note that the Page Control Lock and the RCP Interlock bit are one in
     the same if the Storage Key Assist is being utilized.
     The bits PGSERROR and PGSTRANS are modifiers to the Page Control Lock.
     The following table identifies the meaning of the state of the Page
     Control Lock and it's modifiers:
 PGSPCL  PGSTRANS PGSERROR
     0 0 0 Lock available
     0 0 1 Invalid
     0 1 0 Invalid
     0 1 1 Invalid
     1 0 0 Lock held for short period, spin or skip
     1 0 1 Page in error, only 'release' can manipulate the page
     1 1 0 Lock held for long period, skip or defer. Will be redriven when
     lock is made available
     1 1 1 Invalid
0002    2 Bitstring    1 PGSGFLAG       Virtual Page Flags
          1... ....      PGSINVAL       X'80' No auxiliary storage
                                        assigned Notes : PGSINVAL, in
                                        combination with other PTE,
                                        PGSTE, and storage key status
                                        bits, is used by steal processing
                                        to identify first time reference
                                        pages of zeros which have never
                                        been re-referenced or changed and
                                        can simply be discarded. The
                                        "first time reference page of
                                        zeros" state is identified by the
                                        following bit combination:
                                        noformat PTE: PAGINVAL=0 (page is
                                        valid and resident) PGSTE:
                                        PGSINVAL=1 (no DASD slot
                                        assigned) PGSRCPHR=0
                                        (unreferenced) PGSRCPHC=0
                                        (unchanged) Real frame storage
                                        key: Reference=0 (unreferenced)
                                        Change =0 (unchanged) enoformat
                                        Any resident page in this state
                                        is assumed to be unchanged zeros,
                                        and therefore simply discardable
                                        by steal. No page with non-zero
                                        contents should ever be allowed
                                        to be in this state, or a lost
                                        page will eventually result. The
                                        host change bit, PGSRCPHC, should
                                        be used to indicate that a page
                                        which is unchanged, not already
                                        on DASD, and non-zero, must be
                                        eventually written to DASD. *
                                        Note that both reference bits
                                        (PGSRCPHR and the real storage
                                        frame reference bit) can
                                        "evaporate" to zero over time due
                                        to the action of the reorder
                                        function. Therefore, the fact
                                        that a frame has been referenced,
                                        or setting PGSRCPHR on, can not
                                        prevent a page from eventually
                                        entering this "first time
                                        reference page of zeros" state.
          .1.. ....      PGSSHARE       X'40' Page is a shared page
          ..1. ....      PGS1READ       X'20' ASA may be read only once.
                                        Used for shared pages. After the
                                        first read, this SDF (System Data
                                        File) ASA is to be ignored and
                                        the page left as changed. When
                                        the page is first written, it
                                        will go to a paging space ASA and
                                        this flag wil be turned off.
                                        PGS1READ on implies that page is
                                        read-only for the user.
          ...1 ....      PGSALLOC       X'10' Page in the system address
                                        space (or a system-owned utility
                                        address space) that is allocated,
                                        OR A shared CP page in the
                                        monitor DCSS that CP has
                                        translated and that has not yet
                                        been released by the user
                                        connected to the DCSS. When this
                                        bit is on: 1) The page is never
                                        part of a DASD block; 2) The
                                        associated PGMBK is never paged
                                        out.
          .... 1...      PGSFIXED       X'08' Storage slot permanently
                                        assigned
          .... .1..      PGSIO1ST       X'04' Indicate the first page of
                                        PGMBK has completed I/O.
                                        Serialized via PGSTRANS.
          .... ..1.      PGSIO2ND       X'02' Indicate the second page of
                                        PGMBK has completed I/O.
                                        Serialized via PGSTRANS.
          .... .11.      PGSIOFLG       PGSIO1ST+PGSIO2ND
          00000600       PGSIOMSK       (PGSIO1ST+PGSIO2ND)*256
          .... ...1      PGSREADO       X'01' Storage slot (DASD) is
                                        read-only
0003    3 Bitstring    1 PGSGSTAT       Virtual Page Status bits
          1... ....      PGSALTPT       X'80' Page is defined in an
                                        alternate Page table pointed from
                                        PGMGALTP
          .1.. ....      PGSTRANS       X'40' Page is serialized in long
                                        term
          ..1. ....      PGSPRBN        X'20' ASA is, in fact, a PRBN
          ...1 ....      PGSVMSLK       X'10' Virtual machine storage
                                        lock mode
          .... 1...      PGSXSTOR       X'08' Page is in XSTORE
          .... .1..      PGSBLOCK       X'04' This page is one page in a
                                        block of pages
          .... ..1.      PGSRABI        X'02' This page was read in as
                                        part of a block of pages. This
                                        bit can NOT be checked for PTRM
                                        pages, as it is redefined as
                                        PGSXSTMB in that case.
          .... ...1      PGSERROR       X'01' Page is in error. A storage
                                        error was detected in this page
                                        and the page could not be
                                        recovered. When this bit is set,
                                        VMDRSSFG.VMDRSSUE must be set in
                                        the VMDBK that owns the space.
0003    3 Bitstring    1 PGSGPSTA       Pageable PGMBK Virtual Page
                                        Status bits.
          .... ..1.      PGSXSTMB       X'02' This page (a pageable
                                        PGMBK) itself supports pages in
                                        XSTORE. This bit is only used for
                                        PTRM pages that currently reside
                                        in XSTORE (PGSXSTOR must also be
                                        on if PGSXSTMB is on). Note that
                                        this bit is a redefinition of the
                                        PGSRABI bit, which is acceptable
                                        since pageable PGMBKs (PTRM
                                        pages) are never blocked. .* .*

 

PGS64 Storage Layout

          
*** PGS64 - PAGE STATUS TABLE ENTRY
*
*     +-------------------------------------------------------+
*   0 |                       PGSGENTR                        |
*     +-------------------------------------------------------+
*   8
*
*** PGS64 - PAGE STATUS TABLE ENTRY
          
*** Overlay for PGSGENTR in PGS64
*
*     +---------------------------+---------------------------+
*   0 |         PGS64W0           |         PGS64W1           |
*     +---------------------------+---------------------------+
*
*** Overlay for PGSGENTR in PGS64
          
*** Overlay for PGS64W0 in PGS64
*
*     +------+------+------+------+
*   0 |:GVKEY|:GRCP |:GFLAG|:GSTAT| 4
*     +------+------+------+------+
*
*** Overlay for PGS64W0 in PGS64
          
*** Overlay for PGSGSTAT in PGS64
*
*                          +------+
*   0 ...                3 |:GPSTA| 4
*                          +------+
*
*** Overlay for PGSGSTAT in PGS64

 

PGS64 Cross Reference

Symbol         Dspl Value
-------------- ---- -----
PGSALLOC       0002 10
PGSALTPT       0003 80
PGSBLOCK       0003 04
PGSERROR       0003 01
PGSFIXED       0002 08
PGSGCH         0001 02
PGSGENTR       0000
PGSGFLAG       0002
PGSGLENT       0004 00000008
PGSGNEXT       0008
PGSGPSTA       0003
PGSGRCP        0001
PGSGREF        0001 04
PGSGSTAT       0003
PGSGUEST       0001 06
PGSGVKEY       0000
PGSHOST        0001 60
PGSINVAL       0002 80
PGSIOFLG       0002 06
PGSIOMSK       0002 00000600
PGSIO1ST       0002 04
PGSIO2ND       0002 02
PGSPCL         0001 80
PGSPRBN        0003 20
PGSRABI        0003 02
PGSRCPHC       0001 20
PGSRCPHR       0001 40
PGSREADO       0002 01
PGSSHARE       0002 40
PGSTRANS       0003 40
PGSVKACC       0000 F0
PGSVKACF       0000 F8
PGSVKFET       0000 08
PGSVMSLK       0003 10
PGSXSTMB       0003 02
PGSXSTOR       0003 08
PGS1READ       0002 20
PGS64W0        0000
PGS64W1        0004
RCPGCH         0001 02
RCPGREF        0001 04
RCPGUEST       0001 06
RCPHCH         0001 20
RCPHOST        0001 60
RCPHREF        0001 40
RCPLOCK        0001 80

This information is based on z/VM V4R2.0. Last updated on 17 Oct 2001 at 17:13:04 EDT.
Copyright IBM Corporation, 1990, 2001