DXDA Back to Index page
 
Prolog 
Control Block Contents 
   DXDA DSECT
Storage Layout 
Cross Reference (Contains links to field and bit definitions)
Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.


  DXDA Prolog Top of page
  
 NAME       : HCPDXDA
 DESCRIPTION: Define Extent data area
 DSECT      : DXDA
 FUNCTION   : Maps the contents of the Define Extent data
              area.
 LOCATED BY : HCCWADDR - The Define Extent CCW data address field
              contains the address of the define
              extent data area.
 CREATED BY :
              Storage for this control block cannot be
              specifically allocated/deallocated using
              HCPGETST/HCPRELST.
              Paging I/O manager -
              Data area resides in the HCPPAGBK which
              is allocated by HCPRDA.
              Track cache manager -
              Data area is part of a larger free storage
              area used to build ECKD channel programs
              which is allocated in modules HCPFMU/HCPFMP.
 DELETED BY :
              Storage for this control block cannot be
              specifically allocated/deallocated using
              HCPGETST/HCPRELST.
              Paging I/O manager -
              Data area resides in the HCPPAGBK which
              is deallocated by HCPRDD.
              Track cache manager -
              Data area is part of a larger free storage
              area used to build ECKD channel programs
              which is deallocated in modules HCPFMU/HCPFMP.
 SERIALIZED :
              Paging I/O manager -
              EXPLCKFG - The paging I/O manager uses the exposure
              block lock to serialize this data area.
              Track cache manager -
              TCMTSLK  - Track cache lock
 RELOCATION CONSIDERATIONS : None
 COMMENTS   :
              Paging I/O manager -
              There is one define extent data area for each
              ECKD paging exposure. The data area resides
              in the HCPPAGBK (where the set paging parameter
              CCW would exist (but doesn't for ECKD devices)).
              ALL the Define Extent CCWs in the volume's PIOBKs
              contain the address of this one data area.
              Track cache manager -
              None
 
 
  DXDA Control Block Content Top of page
  




 DXDA DSECT
Top of page


Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      DXDA           Define Extent data area
0000    0 Bitstring   32 DXDAREA (0)    Define extent data area
             Byte 0 (Mask byte)
             Although defined as BITs, the contents of the
             mask byte are, architecturally, multiple codes.
0000    0 Bitstring    1 DXDMASK        Mask
          11.. ....      DXDMWC         X'C0' DXDMWC Mask byte, bits 0
                                        and 1 ------- Codes for use with
                                        DXDMWC
          .... ....      DXDMWCH0       X'00' DXDMWCH0 Permit all write
                                        operations except write HA and
                                        Rec 0
          .1.. ....      DXDMWCIW       X'40' DXDMWCIW Inhibit all write
                                        operations
          1... ....      DXDMWCIF       X'80' DXDMWCIF Permit update
                                        write operations only
          11.. ....      DXDMWCPA       X'C0' DXDMWCPA Permit all write
                                        commands -------
          ..1. ....      DXDMNU         X'20' Mask byte, bit 2 (not used)
          ...1 1...      DXDMSC         X'18' Mask byte, bits 3 and 4
                                        ------- Codes for use with DXDMSC
          .... ....      DXDMSCPA       X'00' Permit all seek commands
          .... 1...      DXDMSCCH       X'08' Permit seek cyl/head
                                        commands
          ...1 ....      DXDMSCH        X'10' Permit seek head commands
          ...1 1...      DXDMSCIS       X'18' Inhibit all seek commands
                                        -------
          .... .11.      DXDMAA         X'06' Mask byte, bits 5 and 6
                                        ------- Codes for use with DXDMAA
          .... ....      DXDMAAN        X'00' Normal authorization
          .... ..1.      DXDMAADE       X'02' Device support
                                        authorization
          .... .1..      DXDMAADI       X'04' Diagnostic authorization
          .... .11.      DXDMAADR       X'06' Device support
                                        authorization with inhibit data
                                        check correction and retry
                                        -------
          .... ...1      DXDMPCI        X'01' Mask byte, bit 7
             Byte 1 (Attribute byte)
             This byte, like the mask byte, contains multiple
             codes. See the explaination of the mask byte for
             possible ways to manipulate the codes.
0001    1 Bitstring    1 DXDATTR        Global Attributes
          11.. ....      DXDAAM         X'C0' DXDAAM Attributes byte,
                                        bits 0 and 1 ------- Codes for
                                        use with DXDAAM
          11.. ....      DXDAAME        X'C0' DXDAAME ECKD mode --------
          ..1. ....      DXDACMON       X'20' CKD conversion mode on
          ...1 11..      DXDASO         X'1C' Attributes byte, bits 3, 4,
                                        and 5 ------- Codes for use with
                                        DXDASO
          .... ....      DXDASONR       X'00' Normal cache replacement
          .... .1..      DXDASOBC       X'04' Bypass cache
          .... 1...      DXDASOIL       X'08' Inhibit cache loading
          .... 11..      DXDASOSA       X'0C' Sequential access
          ...1 .1..      DXDARECA       X'14' Record access
          .... 1...      DXDARECN       X'08' Inverse of record access
                                        -------
          .... ..1.      DXDCFW         X'02' Cache fast write
          .... ...1      DXDDFW         X'01' DASD fast write
             Bytes 2 and 3 (block size)
0002    2 Bitstring    2 DXDBLKSZ       Block size
             Bytes 4 through 7 (global attributes extended
                                 and reserved)
0004    4 Bitstring    4 DXDZEROS (0)   Reserved on some devices
0004    4 Bitstring    3 *
0007    7 Bitstring    1 DXDGLAE        Global attributes extended
          .1.. ....      DXDRDF         X'40' DXDRDF Regular data format
                                        mode
          .... 1...      DXDTSVAL       X'08' DXDTSVAL Time stamp valid
          .... .1..      DXDSTDR0       X'04' DXDSTDR0 Standard R0 Format
          .... ..1.      DXDEXPRM       X'02' DXDEXPRM Extended Parameter
                                        Bit
             Bytes 8 through 11 (beginning extent address)
0008    8 Bitstring    4 DXDBXADR (0)   Beg extent address, CCHH
0008    8 Bitstring    2 DXDBXCC        CC of beginning CCHH
000A   10 Bitstring    2 DXDBXHH        HH of beginning CCHH
             Bytes 12 through 15 (ending extent address)
000C   12 Bitstring    4 DXDEXADR (0)   Ending extent address, CCHH
000C   12 Bitstring    2 DXDEXCC        CC of ending CCHH
000E   14 Bitstring    2 DXDEXHH        HH of ending CCHH
          00000010       DXDNXRCL       *-DXDAREA No XRC Support data
                                        length
             Bytes 16 through 23 (time stamp)
0010   16 Bitstring    8 DXDTSTAM       Time stamp
          00000018       DXDXRCL        *-DXDAREA XRC Support data length
             Bytes 24 through 31
        CHECK TO SEE IF OTHER BITS SHOULD BE ADDED
0018   24 Bitstring    1 DXDEPARM       Global attributes extended
          ..1. ....      DXDEB27        X'20' DXDEB27 Byte 27 has
                                        records/track
0019   25 Bitstring    1 DXDPRIOR       Priority of IO
001A   26 Bitstring    1 DXDXRC         XRC/CH extender
001B   27 Bitstring    1 DXDRCDS        Byte 27 - records per track
001C   28 Bitstring    4 DXDRSRVD       Reserved for hardware use
             Length equates
          00000020       DXDBSIZE       *-DXDAREA Size of DXDA in bytes
          00000004       DXDSIZE        ((*-DXDAREA)+7)/8 Size of DXDA in
                                        DWs
 
 
  DXDA Storage Layout Top of page
  
          
*** DXDA - Define Extent data area
*
*     +------+------+-------------+--------------------+------+
*   0 |:MASK |:ATTR |  DXDBLKSZ   |////////////////////|:GLAE |
*     +------+------+-------------+-------------+------+------+
*   8 |  DXDBXCC    |  DXDBXHH    |  DXDEXCC    |  DXDEXHH    |
*     +-------------+-------------+-------------+-------------+
*  10 |                       DXDTSTAM                        |
*     +------+------+------+------+---------------------------+
*  18 |:EPARM|:PRIOR|DXDXRC|:RCDS |         DXDRSRVD          |
*     +------+------+------+------+---------------------------+
*  20
*
*** DXDA - Define Extent data area
 
 
  DXDA Cross Reference Top of page
  
 
Symbol         Dspl Value
-------------- ---- -----
DXDAAM         0001 C0
DXDAAME        0001 C0
DXDACMON       0001 20
DXDAREA        0000
DXDARECA       0001 14
DXDARECN       0001 08
DXDASO         0001 1C
DXDASOBC       0001 04
DXDASOIL       0001 08
DXDASONR       0001 00
DXDASOSA       0001 0C
DXDATTR        0001
DXDBLKSZ       0002
DXDBSIZE       001C 00000020
DXDBXADR       0008
DXDBXCC        0008
DXDBXHH        000A
DXDCFW         0001 02
DXDDFW         0001 01
DXDEB27        0018 20
DXDEPARM       0018
DXDEXADR       000C
DXDEXCC        000C
DXDEXHH        000E
DXDEXPRM       0007 02
DXDGLAE        0007
DXDMAA         0000 06
DXDMAADE       0000 02
DXDMAADI       0000 04
DXDMAADR       0000 06
DXDMAAN        0000 00
DXDMASK        0000
DXDMNU         0000 20
DXDMPCI        0000 01
DXDMSC         0000 18
DXDMSCCH       0000 08
DXDMSCH        0000 10
DXDMSCIS       0000 18
DXDMSCPA       0000 00
DXDMWC         0000 C0
DXDMWCH0       0000 00
DXDMWCIF       0000 80
DXDMWCIW       0000 40
DXDMWCPA       0000 C0
DXDNXRCL       000E 00000010
DXDPRIOR       0019
DXDRCDS        001B
DXDRDF         0007 40
DXDRSRVD       001C
DXDSIZE        001C 00000004
DXDSTDR0       0007 04
DXDTSTAM       0010
DXDTSVAL       0007 08
DXDXRC         001A
DXDXRCL        0010 00000018
DXDZEROS       0004
 
This information is based on z/VM 7.1.0 Last updated on 22 Jun 2018 at 11:49:17 EDT.
Copyright IBM Corporation, 1990, 2018