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

#### ALOC

Prolog

Control Block Contents
ALOC DSECT

Storage Layout

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'
                                            Notes : ALOCSPOL == PGTSPOOL ==
                                            PGUSPOOL == CPVTEMPS:
    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'
                                            Notes : ALOCSPOL == PGTSPOOL ==
                                            PGUSPOOL == CPVTEMPS:
    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'
                                            Notes : ALOCSPOL == PGTSPOOL ==
                                            PGUSPOOL == CPVTEMPS:
              .... ...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       0010 80
    ALOCDRCT       0000 40
    ALOCDRCT       0001 40
    ALOCDRCT       0010 40
    ALOCFULL       0000 10
    ALOCFULL       0001 10
    ALOCFULL       0010 10
    ALOCMAP        0010
    ALOCMDSK       0010 0C
    ALOCMORE       0010 1C
    ALOCNEXT       0011
    ALOCNFIL       000C 40
    ALOCNTS        0000
    ALOCODE        000D
    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       0010 00
    ALOCYLS        0002
    ALOSTAT        000C

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 17:37:48 EDT.
Copyright IBM Corporation, 1990, 2005