Programming Interface Information:
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DFDA
Control Block Contents
DFDA DSECT
Cross Reference (Contains links to field and bit definitions)
DFDA Prolog
Name : HCPDFDA DESCRIPTION: FBA Define Extent data area DSECT : DFDA Function : Maps the contents of the Define Extent data area for FBA devices. 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 FBA 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 FBA 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 FBA paging exposure. The data area resides in the HCPPAGBK (where the set paging parameter CCW would exist (but doesn't for FBA devices)). ALL the Define Extent CCWs in the volume's PIOBKs contain the address of this one data area. Track cache manager - None
DFDA Control Block Content
DFDA DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure DFDA FBA Define Extent data area 0000 0 Bitstring 16 DFDAREA (0) FBA 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 DFDMASK Mask 11.. .... DFDMWC X'C0' Mask byte, bits 0 and 1 ------- Codes for use with DFDMWC .... .... DFDMWCNF X'00' Non-formatting write permitted, formatting wirte inhibited .1.. .... DFDMWCIW X'40' Inhibit all write operations 1... .... DFDMWCRS X'80' Reserved 11.. .... DFDMWCPA X'C0' Permit all write commands ..1. .... DFDMB2 X'20' Mask, bit 2 (not used) zeroes ...1 .... DFDMB3 X'10' Mask, bit 3 (not used) zeroes .... 1... DFDMB4 X'08' Mask, bit 4 ------- Codes for use with DFDMB4 .... .... DFDMB4DA X'00' Data area .... 1... DFDMB4ND X'08' Non-data area .... .11. DFDMB5 X'06' Mask byte, bit 5 ------- Codes for use with DFDMB5 .... .... DFDMB5ID X'00' Inhibit diagnostic commands .... .11. DFDMB5PD X'06' Permit diagnostic commands .... ..11 DFDMB6 X'03' Mask byte, bits 6 and 7 ------- Codes for use with DFDMB6 .... .... DFDMB6CE X'00' CE area .... ...1 DFDMB6S1 X'01' Subsystem 1 area .... ..1. DFDMB6S2 X'02' Subsystem 2 area .... ..11 DFDMB6RS X'03' Reserved Byte 1 (must be zero) 0001 1 Bitstring 1 DFDZERO Reserved, must be zero Bytes 2 and 3 (block size) 0002 2 Bitstring 2 DFDBLKSZ Block size in bytes Bytes 4 through 7 (Extent Locator) 0004 4 Bitstring 4 DFDEXTLC Extent Locator for this extent Bytes 8 through 11 (beginning extent address) 0008 8 Bitstring 4 DFDBXBEG Beg extent address in block number Bytes 12 through 15 (ending extent address) 000C 12 Bitstring 4 DFDEXEND Ending extent block number Length equates 00000010 DFDBSIZE *-DFDAREA Size of DFDA in bytes 00000002 DFDSIZE ((*-DFDAREA)+7)/8 Size of DFDA in DWs
DFDA Storage Layout
*** DFDA - FBA Define Extent data area * * +------+------+-------------+---------------------------+ * 0 |:MASK |:ZERO | DFDBLKSZ | DFDEXTLC | * +------+------+-------------+---------------------------+ * 8 | DFDBXBEG | DFDEXEND | * +---------------------------+---------------------------+ * 10 * *** DFDA - FBA Define Extent data area
DFDA Cross Reference
Symbol Dspl Value -------------- ---- ----- DFDAREA 0000 DFDBLKSZ 0002 DFDBSIZE 000C 00000010 DFDBXBEG 0008 DFDEXEND 000C DFDEXTLC 0004 DFDMASK 0000 DFDMB2 0000 20 DFDMB3 0000 10 DFDMB4 0000 08 DFDMB4DA 0000 00 DFDMB4ND 0000 08 DFDMB5 0000 06 DFDMB5ID 0000 00 DFDMB5PD 0000 06 DFDMB6 0000 03 DFDMB6CE 0000 00 DFDMB6RS 0000 03 DFDMB6S1 0000 01 DFDMB6S2 0000 02 DFDMWC 0000 C0 DFDMWCIW 0000 40 DFDMWCNF 0000 00 DFDMWCPA 0000 C0 DFDMWCRS 0000 80 DFDSIZE 000C 00000002 DFDZERO 0001
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