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Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
DXDA
Control Block Contents
DXDA DSECT
Cross Reference (Contains links to field and bit definitions)
DXDA Prolog
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
DXDA DSECT
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 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 (reserved) 0018 24 Bitstring 8 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
*** DXDA - Define Extent data area
*
* +------+------+-------------+--------------------+------+
* 0 |:MASK |:ATTR | DXDBLKSZ |////////////////////|:GLAE |
* +------+------+-------------+-------------+------+------+
* 8 | DXDBXCC | DXDBXHH | DXDEXCC | DXDEXHH |
* +-------------+-------------+-------------+-------------+
* 10 | DXDTSTAM |
* +-------------------------------------------------------+
* 18 | DXDRSRVD |
* +-------------------------------------------------------+
* 20
*
*** DXDA - Define Extent data area
DXDA Cross Reference
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 0018 00000020 DXDBXADR 0008 DXDBXCC 0008 DXDBXHH 000A DXDCFW 0001 02 DXDDFW 0001 01 DXDEXADR 000C DXDEXCC 000C DXDEXHH 000E 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 DXDRDF 0007 40 DXDRSRVD 0018 DXDSIZE 0018 00000004 DXDSTDR0 0007 04 DXDTSTAM 0010 DXDTSVAL 0007 08 DXDXRCL 0010 00000018 DXDZEROS 0004
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