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Programming Interface Information:
This information is NOT
intended to be
used as Programming Interfaces of VM/ESA. It is to be used for diagnosis only. |
DXDA
Cross Reference (Contains links to field and bit definitions)
DXDA Prolog
Name : HCPDXDA
Description: Define Extent data area
STATUS : VM/ESA Version 2, Release 3.0
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 HCPFTU/HCPFTP.
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 HCPFTU/HCPFTP.
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
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 16 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' Mask byte, bits 0 and 1 ------- Codes for use with DXDMWC .... .... DXDMWCH0 X'00' Permit all write operations except write HA and Rec 0 .1.. .... DXDMWCIW X'40' Inhibit all write operations 1... .... DXDMWCIF X'80' Permit update write operations only 11.. .... DXDMWCPA X'C0' 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' Attributes byte, bits 0 and 1 ------- Codes for use with DXDAAM 11.. .... DXDAAME X'C0' 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' Regular data format mode .... .1.. DXDSTDR0 X'04' 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 Length equates 00000010 DXDBSIZE *-DXDAREA Size of DXDA in bytes 00000002 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 * *** DXDA - Define Extent data area
DXDA Cross Reference
(contains links to field and bit definitions)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 000E 00000010
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
DXDRDF 0007 40
DXDSIZE 000E 00000002
DXDSTDR0 0007 04
DXDZEROS 0004
Last updated on 3 Aug 1999 at 11:53:51 EDT.
Copyright IBM Corporation, 1990, 1999