Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
PSYBK
Control Block Contents
PSYBK DSECT
Cross Reference (Contains links to field and bit definitions)
PSYBK Prolog
Name : HCPPSYBK Description: Persistent System Permanent Free Storage Frame Header Control Block 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
Copyright IBM Corporation, 1990, 2001