In a message dated 9/13/2007 5:59:21 A.M. Central Daylight Time, [EMAIL PROTECTED] writes: >1-3 extents occupy one VTOC block, next extents if available occupy another VTOC block. In other words 100+ extents dataset occupy the same VTOC space as 4 extent dataset. This is not totally correct. The first 3 extents occupy the Format 1 DSCB (Data Set Control Block), which must be defined in the VTOC for every new data set. Each successive set of 13 extents occupy one more VTOC block called the Format 3 DSCB. Thus 100 extents would require 9 DSCBs (the ninth one would only contain information on the last 6 extents). This assumes that any possible extent consolidation has already occurred as each new extent is allocated. Bill Fairchild Plainfield, IL
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