|
Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM. |
ALOC
Control Block Contents
ALOC DSECT
Cross Reference (Contains links to field and bit definitions)
ALOC Prolog
NAME : HCPALOC
DESCRIPTION: DASD VOLUME ALLOCATION BLOCK
DSECT : ALOC
FUNCTION : Maps the DASD allocation record on DASD for
CYLINDER-BASED ALLOCATION MAPPING.
(ECKD/CKD DASD with less than or equal to
ALOCMAXCM cylinders.)
LOCATED BY : The allocation record resides on CP formatted CKD
and ECKD DASD on cylinder 0, head 0, record 4. It
exists only temporarily in storage.
CREATED BY : ICKDSF when a CKD or ECKD DASD
with less than or equal to ALOCMAXCM cylinders
is formatted for CP use.
DELETED BY : Exists in storage only until the in-storage
representation of the allocation map (HCPVEXBK,
HCPEXTBK) is built.
Comments :
If a CKD or ECKD DASD with more than ALOCMAXCM cylinders
is formatted by ICKDSF, then an EXTENT-BASED ALLOCATION
MAPPING is used.
ALOC DSECT maps all CYLINDER-BASED ALLOCATION MAPPING.
ALOCEXT DSECT maps all EXTENT-BASED ALLOCATION MAPPING.
ALOC Control Block Content
ALOC DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure ALOC DASD VOLUME ALLOCATION BLOCK 0000 0 Bitstring 1 ALOCNTS VOLUME TYPE CONTENTS THIS BYTE CONTAINS THE RESULTING BIT CONFIGURATION OBTAINED BY ORING ALL USE FLAGS THAT REPRESENT TYPE OF CYLINDERS ALLOCATED ON THIS VOLUME. 1... .... ALOCATED X'80' CYLINDER IS CURRENTLY IN USE THIS TYPE OF ALLOCATION SHOULD ONLY BE USED IN CONJUNCTION WITH THE TYPE 'DRCT' .1.. .... ALOCDRCT X'40' ALLOCATION TYPE 'DRCT' ..1. .... ALOCTDSK X'20' ALLOCATION TYPE 'TDSK' ...1 .... ALOCFULL X'10' CYLINDER IS FULL NOTE- ALOCFULL is used only in combination with SPOL & PAGE .... 1... ALOCPERM X'08' ALLOCATION TYPE 'PERM' .... ..1. ALOCSPOL X'02' ALLOCATION TYPE 'SPOL' .... ...1 ALOCPAGE X'01' ALLOCATION TYPE 'PAGE' Notes : ALOCPAGE == PGTPAGE == PGUPAGE == CPVTEMPP: .... 11.. ALOCMDSK X'0C' Allocation type 'MDSK' ...1 11.. ALOCMORE X'1C' Allocation type 'MORE' 1... .... ALOCDRAN X'80' Device is permanently drained. .... .... ALOCUNDF X'00' Undefined allocation type; these cylinders/pages are ignored 0001 1 Bitstring 1 ALOAVAIL AVAILABILITY OF TYPES 1... .... ALOCATED X'80' CYLINDER IS CURRENTLY IN USE THIS TYPE OF ALLOCATION SHOULD ONLY BE USED IN CONJUNCTION WITH THE TYPE 'DRCT' .1.. .... ALOCDRCT X'40' ALLOCATION TYPE 'DRCT' ..1. .... ALOCTDSK X'20' ALLOCATION TYPE 'TDSK' ...1 .... ALOCFULL X'10' CYLINDER IS FULL NOTE- ALOCFULL is used only in combination with SPOL & PAGE .... 1... ALOCPERM X'08' ALLOCATION TYPE 'PERM' .... ..1. ALOCSPOL X'02' ALLOCATION TYPE 'SPOL' .... ...1 ALOCPAGE X'01' ALLOCATION TYPE 'PAGE' Notes : ALOCPAGE == PGTPAGE == PGUPAGE == CPVTEMPP: .... 11.. ALOCMDSK X'0C' Allocation type 'MDSK' ...1 11.. ALOCMORE X'1C' Allocation type 'MORE' 1... .... ALOCDRAN X'80' Device is permanently drained. .... .... ALOCUNDF X'00' Undefined allocation type; these cylinders/pages are ignored 0002 2 Signed 2 ALOCYLS NUMBER OF CYLINDERS ON DEVICE Note that the high order bit in ALOCYLS (3rd byte of the allocation map) is reserved. It indicates whether or not the map is an extent-based map. In this cylinder-based form of the allocation map, the bit is off. 0004 4 Signed 4 * (2) Reserved for IBM use 000C 12 Bitstring 1 ALOSTAT VOLUME STATUS FLAG .1.. .... ALOCNFIL X'40' ALL 'CP SPACE' ON THIS VOLUME IS FORMATTED WITHOUT FILLER RECORDS 000D 13 Bitstring 1 ALOCODE Index into CPVOL list 000E 14 Signed 2 * RESERVED FOR FUTURE IBM USE 0010 16 Bitstring 8 ALOCMAP (0) START OF VARIABLE LENGTH DATA 1... .... ALOCATED X'80' CYLINDER IS CURRENTLY IN USE THIS TYPE OF ALLOCATION SHOULD ONLY BE USED IN CONJUNCTION WITH THE TYPE 'DRCT' .1.. .... ALOCDRCT X'40' ALLOCATION TYPE 'DRCT' ..1. .... ALOCTDSK X'20' ALLOCATION TYPE 'TDSK' ...1 .... ALOCFULL X'10' CYLINDER IS FULL NOTE- ALOCFULL is used only in combination with SPOL & PAGE .... 1... ALOCPERM X'08' ALLOCATION TYPE 'PERM' .... ..1. ALOCSPOL X'02' ALLOCATION TYPE 'SPOL' .... ...1 ALOCPAGE X'01' ALLOCATION TYPE 'PAGE' Notes : ALOCPAGE == PGTPAGE == PGUPAGE == CPVTEMPP: .... 11.. ALOCMDSK X'0C' Allocation type 'MDSK' ...1 11.. ALOCMORE X'1C' Allocation type 'MORE' 1... .... ALOCDRAN X'80' Device is permanently drained. .... .... ALOCUNDF X'00' Undefined allocation type; these cylinders/pages are ignored 0010 16 Bitstring 1 ALOCBYTE Allocation byte for a single cylinder 0011 17 Bitstring 1 ALOCNEXT Position of next allocation byte
ALOC Storage Layout
*** ALOC - DASD VOLUME ALLOCATION BLOCK
*
* +------+------+-------------+---------------------------+
* 0 |:CNTS |:AVAIL| ALOCYLS |///////////////////////////|
* +------+------+-------------+------+------+-------------+
* 8 |///////////////////////////|:STAT |:CODE |/////////////|
* +---------------------------+------+------+-------------+
*
*** ALOC - DASD VOLUME ALLOCATION BLOCK
*** Overlay for ALOCMAP in ALOC
*
* +------+------+
* 10 |:CBYTE|:CNEXT| 12
* +------+------+
*
*** Overlay for ALOCMAP in ALOC
ALOC Cross Reference
Symbol Dspl Value -------------- ---- ----- ALOAVAIL 0001 ALOCATED 0000 80 ALOCATED 0001 80 ALOCATED 0010 80 ALOCBYTE 0010 ALOCDRAN 0000 80 ALOCDRAN 0001 80 ALOCDRAN 0010 80 ALOCDRCT 0000 40 ALOCDRCT 0001 40 ALOCDRCT 0010 40 ALOCFULL 0000 10 ALOCFULL 0001 10 ALOCFULL 0010 10 ALOCMAP 0010 ALOCMDSK 0000 0C ALOCMDSK 0001 0C ALOCMDSK 0010 0C ALOCMORE 0000 1C ALOCMORE 0001 1C ALOCMORE 0010 1C ALOCNEXT 0011 ALOCNFIL 000C 40 ALOCNTS 0000 ALOCODE 000D ALOCPAGE 0000 01 ALOCPAGE 0001 01 ALOCPAGE 0010 01 ALOCPERM 0000 08 ALOCPERM 0001 08 ALOCPERM 0010 08 ALOCSPOL 0000 02 ALOCSPOL 0001 02 ALOCSPOL 0010 02 ALOCTDSK 0000 20 ALOCTDSK 0001 20 ALOCTDSK 0010 20 ALOCUNDF 0000 00 ALOCUNDF 0001 00 ALOCUNDF 0010 00 ALOCYLS 0002 ALOSTAT 000C
Last updated on 5 Jun 2001 at 17:10:57 EDT.
Copyright IBM Corporation, 1990, 2001