RECELCK RECBLOK maintains the correlation of DISD storage pages to a specific cylinder location.
Also maintained is a bit map to indicate the page slotsavailable for data page storage.
TheRDEVRECS field and the BDEVPAGE field of the RDEVELCK point to BECELCK. o
8Hexadecimal Displacement
------------0 4
6
7
8BECPNT RECCYL I R*1 I B*2 RECMAP (128 pages maximum) Field
Name Field Description, Contents,Meaning BECPNT DS 1F RECCYL DS 1B RECUSED DS 1X RECMAX DS 1X BECMAP DS 1L
Bits defined inRECMAP O-=-page-is-available R*1
B*2
1 -Page has been assigned
--------------------------------------Pointer to next RECBLOK on cbain
Cylinder address for pages in this blockNumber of pages currently in use Maximum numter of pages available Page allocation bit map (128 Fages maximum) Although the size of RECMIP is fixed, the maximum number of pages
available on a cylinder is device dependent. Bits corresponding topages not physically present on a cylinder are set to 1. RECSIZE EQU (*-BECB10Kj/8 BECELOK size in doutlewords
Section 1.CP Data Areas and Centrel Blocks 89
Also maintained is a bit map to indicate the page slots
The
8
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6
7
8
Name Field Description, Contents,
Bits defined in
B*2
1 -
--------------------------------------
Cylinder address for pages in this block
available on a cylinder is device dependent. Bits corresponding to
Section 1.