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Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
XBLBK
Control Block Contents
XBLBK DSECT
Cross Reference (Contains links to field and bit definitions)
XBLBK Prolog
NAME : HCPXBLBK DESCRIPTION: XA buffer list block. DSECT : XBLBK FUNCTION : This block is used to keep track of the real buffers that contain virtual device information. LOCATED BY : Addressability is established when obtaining FREE storage. The block is not anchored anywhere. CREATED BY : HCPIIR when saving the virtual device information. - HCPNSE when restoring the virtual device information. DELETED BY : HCPNSE will return the block to FREE storage. RELOCATION CONSIDERATIONS : None COMMENTS : This is a variable length block. The size is the header, plus one-half the number of real page buffers, plus one.
XBLBK Control Block Content
XBLBK DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure XBLBK XA buffer list block. 0000 0 Bitstring 8 * Reserved for future IBM use. 0008 8 Signed 4 XBLDEVCT COUNT OF THE NUMBER OF DEVICES. 000C 12 Signed 4 XBLRBFCT COUNT OF REAL BUFFER ADDRESSES. 00000002 XBLHDRSZ (((*-XBLBK)+7)/8) This is the header size in DW. 0010 16 Signed 4 XBLDATA (0) Start of variable length data. 0010 16 Signed 4 XBLRBFAD The first real buffer address starts here. 00000004 XBLRBSIZ (*-XBLRBFAD) This is the size of an entry for a real buffer.
XBLBK Storage Layout
*** XBLBK - XA buffer list block. * * +-------------------------------------------------------+ * 0 |///////////////////////////////////////////////////////| * +---------------------------+---------------------------+ * 8 | XBLDEVCT | XBLRBFCT | * +---------------------------+---------------------------+ * *** XBLBK - XA buffer list block. *** Overlay for XBLDATA in XBLBK * * +---------------------------+ * 10 | XBLRBFAD | 14 * +---------------------------+ * *** Overlay for XBLDATA in XBLBK
XBLBK Cross Reference
Symbol Dspl Value -------------- ---- ----- XBLDATA 0010 XBLDEVCT 0008 XBLHDRSZ 000C 00000002 XBLRBFAD 0010 XBLRBFCT 000C XBLRBSIZ 0010 00000004
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