Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
BIOPG
Control Block Contents
BIOPG DSECT
Cross Reference (Contains links to field and bit definitions)
BIOPG Prolog
NAME : HCPBIOPG DESCRIPTION: DASD Block I/O Storage Management Block DSECT : BIOPG aka BIOBG FUNCTION : Contains header information and room to allocate I/O related control blocks for DIAGNOSE 18, A4, 250 and *BLOCKIO. LOCATED BY : BIOPGNXT and BIOPGPRV links the list together (caller must remember the start) CREATED BY : HCPDPSGP DELETED BY : HCPDPSRP, HCPDPSCU RELOCATION CONSIDERATIONS : None COMMENTS : This block comes in two sizes: 2040 bytes and 4088 bytes. The size chosen is determined by the length of the request. The BIOPG consists of a header and available storage. Its used as a source for control blocks. The HCPDPCUT macro will obtain storage from the BIOPG to create control blocks such as the IORBK and DVIOPs. This avoids the need to call HCPFREE for each needed control block. When the storage in one BIOPG is used up, another is obtained and linked to the previous using BIOPGNXT.
BIOPG Control Block Content
BIOPG DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure BIOPG DASD Block I/O Storage Management Block 0000 0 Signed 4 BIOPGNXT Pointer to the next BIOPG block (0 if no more) 0004 4 Signed 4 * Reserved for IBM use 0008 8 Signed 4 BIOPGAV Pointer to the next available storage location 000C 12 Signed 4 BIOPGEND Address of BIOBGEND/BIOPEND 0010 16 Bitstring 2024 BIOPDATA Size of data area 000007F8 BIOPEND * Byte following end of BIOPG 000000FF BIOPGDWS (((*-BIOPG)+7)/8) Size in doublewords Redefine the data area for the larger sized block. This larger block has a separate entry in the CBITABLE and uses BIOBG as it's ID. 0010 16 Bitstring 4072 BIOBDATA Size of data area 00000FF8 BIOBGEND * Byte following end of BIOBG 000001FF BIOBGDWS (((*-BIOPG)+7)/8) Size in doublewords
BIOPG Storage Layout
*** BIOPG - DASD Block I/O Storage Management Block * * +---------------------------+---------------------------+ * 0 | BIOPGNXT |///////////////////////////| * +---------------------------+---------------------------+ * 8 | BIOPGAV | BIOPGEND | * +---------------------------+---------------------------+ * 10 | | * = BIOPDATA = * | | * +-------------------------------------------------------+ * 7F8 * *** BIOPG - DASD Block I/O Storage Management Block *** Overlay for BIOPDATA in BIOPG * * +-------------------------------------------------------+ * 10 | | * = BIOBDATA = * | | * +-------------------------------------------------------+ * FF8 * *** Overlay for BIOPDATA in BIOPG
BIOPG Cross Reference
Symbol Dspl Value -------------- ---- ----- BIOBDATA 0010 BIOBGDWS 0010 000001FF BIOBGEND 0010 00000FF8 BIOPDATA 0010 BIOPEND 0010 000007F8 BIOPGAV 0008 BIOPGDWS 0010 000000FF BIOPGEND 000C BIOPGNXT 0000
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