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Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
SUBBK
Control Block Contents
SUBBK DSECT
Cross Reference (Contains links to field and bit definitions)
SUBBK Prolog
Name : HCPSUBBK
Description: Subpool Data Area Block
DSECT : SUBBK
Function :
Maps each of the free storage subpool data area
elements.
Created by : Never allocated
Deleted by : Never deallocated
Notes : This DSECT is used to map the free storage subpool
data area groups located in HCPRSM. Specifically,
HCPRSMSS (regular free storage subpools) and
HCPRSMVT (V=R free storage subpools).
Each data area group consists of multiple data
area elements.
SUBBK Control Block Content
SUBBK DSECT
Hex Dec Type/Val Lng Label (dup) Comments
---- ---- --------- ---- -------------- --------
0000 0 Structure SUBBK Subpool Data Area Block
Format 0 ("old style") SUBBK format used for subpools for the following
types of subpooled free storage:
- V=R free storage (HCPFRFV* entry points, HCPVRS) - Virtual Free
Storage (HCPVFM) - Aligned Free Storage (HCPAFS) - Verifiable Free
Storage (HCPVCB)
0000 0 Signed 4 SUBLOCK Subpool lock word
0004 4 Signed 4 SUBSIZE Integral size (in DWDS) of
subpool block including FRERECL
0008 8 Address 4 SUBANCH Pointer to first FRMTE for
subpooled free storage, or 1st
available block for V=R
000C 12 Signed 4 SUBRCNT Count of requests this size
0010 16 Signed 4 SUBODWD Count of DWD currently in use
(multiple of SUBSIZE)
0014 20 Signed 4 SUBCDWD Count of DWDS now on chain
0018 24 Signed 4 SUBUDWD Count of actual DWD usage (does
not include internal
fragmentation)
001C 28 Signed 4 * Reserved for IBM use
0020 32 Signed 4 * Reserved for IBM use
00000024 SUBESZ *-SUBBK Size of one subpool entry
Format 1 ("new/fast style") SUBBK format used for standard short term
free storage, including "fast allocated" free storage control blocks.
0000 0 Bitstring 1 SUBTSLK Subpool lock byte
0001 1 Bitstring 1 * Reserved for IBM use
0002 2 Signed 2 SUBBSIZE Size in bytes (including
header/trailer) of each block on
this subpool
0004 4 Signed 2 SUBMAXBS Maximum number of blocks that fit
in one frame
0006 6 Signed 2 SUBMTFCT Count of frames on SUBMTFTE empty
frame queue for this subpool
Notes : The following three
fields (SUBFRETS, SUBBLOCK, and
SUBTOTRQ) must remain contiguous
and in order, as there is
performance sensitive code in the
free storage allocation and
deallocation paths which
references two adjacent fields
(SUBBLOCK and SUBTOTRQ for
allocation, SUBFRETS and SUBBLOCK
for deallocation) with a single
STM instruction
0008 8 Signed 4 SUBFRETS Total count of returns to this
free storage subpool
000C 12 Signed 4 SUBBLOCK Anchor for blocks on this subpool
0010 16 Signed 4 SUBTOTRQ Total count of requests against
this subpool
SUBFRETS and SUBBLOCK remain contiguous
SUBBLOCK and SUBTOTRQ remain contiguous
0014 20 Signed 4 SUBMTFTE FRMTE address of 1st empty frame
on queue. FFS mark end of chain.
0018 24 Signed 4 SUBCLCTP Collection pile
001C 28 Signed 4 SUBXTNCT Count of extends
0020 32 Signed 2 SUBFRMCT Count of frames on pool
0022 34 Signed 2 SUBINUSE Count of blocks in use on this
subpool
00000024 SUBNEXT * Address of next SUBBK
00000024 SUBSSZ *-SUBBK Size of one standard
short term free storage SUBBK
entry
00000002 SUBOFFSH 2 Number of bits to shift a
subpool number to get the index
into the HCPFRESO SUBBK offsets
table for the subpool's SUBBK
Format 1 SUBBKs are the same length
SUBBK Storage Layout
*** SUBBK - Subpool Data Area Block
*
* +---------------------------+---------------------------+
* 0 | SUBLOCK | SUBSIZE |
* +---------------------------+---------------------------+
* 8 | SUBANCH | SUBRCNT |
* +---------------------------+---------------------------+
* 10 | SUBODWD | SUBCDWD |
* +---------------------------+---------------------------+
* 18 | SUBUDWD |///////////////////////////|
* +---------------------------+---------------------------+
* 20 |///////////////////////////| 24
* +---------------------------+
*
*** SUBBK - Subpool Data Area Block
*** Overlay for SUBLOCK in SUBBK
*
* +------+------+-------------+-------------+-------------+
* 0 |:TSLK |//////| SUBBSIZE | SUBMAXBS | SUBMTFCT |
* +------+------+-------------+-------------+-------------+
* 8 | SUBFRETS | SUBBLOCK |
* +---------------------------+---------------------------+
* 10 | SUBTOTRQ | SUBMTFTE |
* +---------------------------+---------------------------+
* 18 | SUBCLCTP | SUBXTNCT |
* +-------------+-------------+---------------------------+
* 20 | SUBFRMCT | SUBINUSE | 24
* +-------------+-------------+
*
*** Overlay for SUBLOCK in SUBBK
SUBBK Cross Reference
Symbol Dspl Value -------------- ---- ----- SUBANCH 0008 SUBBLOCK 000C SUBBSIZE 0002 SUBCDWD 0014 SUBCLCTP 0018 SUBESZ 0020 00000024 SUBFRETS 0008 SUBFRMCT 0020 SUBINUSE 0022 SUBLOCK 0000 SUBMAXBS 0004 SUBMTFCT 0006 SUBMTFTE 0014 SUBNEXT 0022 00000024 SUBODWD 0010 SUBOFFSH 0022 00000002 SUBRCNT 000C SUBSIZE 0004 SUBSSZ 0022 00000024 SUBTOTRQ 0010 SUBTSLK 0000 SUBUDWD 0018 SUBXTNCT 001C
Copyright IBM Corporation, 1990, 2001