PRQHD - 64-bit CP - V4R4.0

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

#### PRQHD

Prolog

Control Block Contents
PRQHD DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### PRQHD Prolog

     Name       : HCPPRQHD
     Description: PERSYS Persistent SYSPERM Free Storage
                  Queue Header Control Block
     DSECT      : PRQHD
     Function   : Map the PERSYS persistent SYSPERM free storage
                  queue header
     Located by : Resides at SYSPRQHD in SYSCM
     Created by : Created as part of SYSCM at system generation
     Deleted by : Never deleted.
     Serialized : Regular free storage frame serialization -
                  FSDVMLK located at HCPRSMFL
     Comments   :
                  There is only one PRQHD in the system, and it resides in
                  SYSCM at SYSPRQHD.  PRQHD cannot be dynamically allocated
                  or destroyed.

#### PRQHD Control Block Content

#### PRQHD DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      PRQHD          PERSYS Persistent SYSPERM Free
                                            Storage
    0000    0 Address      4 PRQFWD         Forward pointer to the first
                                            PERSYS free storage frame's PSYBK
                                            header. If there are no PERSYS
                                            free storage frames on the queue,
                                            points to PRQHD itself.
    0004    4 Address      4 PRQBWD         Backward pointer to the last
                                            PERSYS free storage frame's PSYBK
                                            header. If there are no PERSYS
                                            free storage frames on the queue,
                                            points to PRQHD itself.
    0008    8 Signed       4 PRQFRMCT       Count of frames on queue
    000C   12 Bitstring    1 PRQHSTAT       Queue status byte
              1... ....      PRQHFLUX       X'80' Queue is in flux, recovery
                                            not possible
              .1.. ....      PRQHSURV       X'40' PERSYS free storage has
                                            survived a bounce from a previous
                                            IPL (this IPL is not a PERSYS
                                            "base" IPL).
    000D   13 Bitstring    3 *              Reserved for IBM use
    0010   16 Dbl-Word     8 * (0)
    0010   16 Dbl-Word     8 PRQTODST       "Base" IPL TOD timestamp. This is
                                            the TOD timestamp of the original
                                            IPL since which PERSYS storage
                                            has survived.
              00000018       PRQLEN         *-PRQHD Length, in bytes, of
                                            PRQHD
              00000003       PRQSIZE        (*-PRQHD+7)/8 Size, in
                                            doublewords, of PRQHD

#### PRQHD Storage Layout

    *** PRQHD - PERSYS Persistent SYSPERM Free Storage
    *
    *     +---------------------------+---------------------------+
    *   0 |          PRQFWD           |          PRQBWD           |
    *     +---------------------------+------+--------------------+
    *   8 |         PRQFRMCT          |:HSTAT|////////////////////|
    *     +---------------------------+------+--------------------+
    *  10 |                       PRQTODST                        |
    *     +-------------------------------------------------------+
    *  18
    *
    *** PRQHD - PERSYS Persistent SYSPERM Free Storage

#### PRQHD Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    PRQBWD         0004
    PRQFRMCT       0008
    PRQFWD         0000
    PRQHFLUX       000C 80
    PRQHSTAT       000C
    PRQHSURV       000C 40
    PRQLEN         0010 00000018
    PRQSIZE        0010 00000003
    PRQTODST       0010

This information is based on z/VM V4R4.0. Last updated on 30 Jul 2003 at 13:07:20 EDT.
Copyright IBM Corporation, 1990, 2003