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

#### PSYBK

Prolog

Control Block Contents
PSYBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### PSYBK Prolog

     Name       : HCPPSYBK
     Description: Persistent System Permanent Free Storage
                  Frame Header Control Block
     COPYRIGHT -
                  THIS MODULE IS "RESTRICTED MATERIALS OF IBM"
                  5654-A17 (C) COPYRIGHT IBM CORP. - 1995, 2001
                  LICENSED MATERIALS - PROPERTY OF IBM
     DSECT      : PSYBK
     Function   : Map the header of Persistent System Permanent
                  Free Storage frames
     Located by : PRQHDR, PSYFWD
     Created by : HCPFRDPR
     Deleted by : HCPFRET
     Serialized : Regular free storage frame serialization -
                  FSDVMLK located at HCPRSMFL
     Notes      : PSYBKs are always, and only, allocated as the very first
                  block in PERSYS free storage frames.  They serve as the
                  PERSYS free storage frame header, and are pre-allocated
                  out of the frame before the first request for which the
                  frame was obtained is satisfied and allocated.  All
                  PERSYS free storage frames must have a PSYBK as the first
                  control block, and no PSYBKs may be allocated anywhere
                  else.  PSYBKs are only deleted when the PERSYS free
                  storage frame is otherwise empty and the frame is being
                  reclaimed and returned to the available list for other
                  uses.

#### PSYBK Control Block Content

#### PSYBK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      PSYBK          Persistent System Permanent Free
                                            Storage
    0000    0 Signed       4 PSYFWD         Forward pointer to the next
                                            persistent free storage frame's
                                            PSYBK header, or PRQHD address if
                                            this is the last PSYBK on the
                                            queue.
    0004    4 Signed       4 PSYBWD         Backward pointer to the previous
                                            persistent free storage frame's
                                            PSYBK header, or PRQHD address if
                                            this is the first PSYBK on the
                                            queue.
    0008    8 Bitstring    1 PSYCODE        FRMCODE that must match FRMCSB0
                                            and be equal to FRMPERSY for
                                            persistent free storage frames
                                            and their PSYBK headers
    0009    9 Bitstring    3 *              Reserved for IBM use
    000C   12 Signed       2 PSYVMFRG       Shadow copy of FRMVMFRG so that
                                            we can restore persistent free
                                            storage FRMTE after a bounce
    000E   14 Signed       2 PSYDWUSE       Shadow copy of FRMDWUSE so that
                                            we can restore persistent free
                                            storage FRMTE after a bounce
    0010   16 Signed       4 PSYCHN         Shadow copy of FRMCHN so that we
                                            can restore persistent free
                                            storage FRMTE after a bounce
    0014   20 Signed       4 *              Reserved for IBM use
    0018   24 Dbl-Word     8 PSYTODST       "Base" IPL TOD timestamp. This is
                                            the TOD timestamp of the original
                                            IPL since which PERSYS storage
                                            has survived.
              00000020       PSYLEN         *-PSYBK Length, in bytes, of
                                            PSYBK
              00000004       PSYSIZE        (*-PSYBK+7)/8 Size, in
                                            doublewords, of PSYBK

#### PSYBK Storage Layout

    *** PSYBK - Persistent System Permanent Free Storage
    *
    *     +---------------------------+---------------------------+
    *   0 |          PSYFWD           |          PSYBWD           |
    *     +------+--------------------+-------------+-------------+
    *   8 |:CODE |////////////////////|  PSYVMFRG   |  PSYDWUSE   |
    *     +------+--------------------+-------------+-------------+
    *  10 |          PSYCHN           |///////////////////////////|
    *     +---------------------------+---------------------------+
    *  18 |                       PSYTODST                        |
    *     +-------------------------------------------------------+
    *  20
    *
    *** PSYBK - Persistent System Permanent Free Storage

#### PSYBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    PSYBWD         0004
    PSYCHN         0010
    PSYCODE        0008
    PSYDWUSE       000E
    PSYFWD         0000
    PSYLEN         0018 00000020
    PSYSIZE        0018 00000004
    PSYTODST       0018
    PSYVMFRG       000C

This information is based on z/VM V4R3.0. Last updated on 30 Apr 2002 at 17:23:49 EDT.
Copyright IBM Corporation, 1990, 2002