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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. |
PSYBK
Cross Reference (Contains links to field and bit definitions)
PSYBK Prolog
Name : HCPPSYBK
Description: Persistent System Permanent Free Storage
Frame Header Control Block
STATUS : VM/ESA Version 2, Release 4.0
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
(contains links to field and bit definitions)Symbol Dspl Value -------------- ---- -----PSYBWD 0004
PSYCHN 0010
PSYCODE 0008
PSYDWUSE 000E
PSYFWD 0000
PSYLEN 0018 00000020
PSYSIZE 0018 00000004
PSYTODST 0018
PSYVMFRG 000C
Last updated on 3 Aug 1999 at 12:25:01 EDT.
Copyright IBM Corporation, 1990, 1999