On Sat, 7 Dec 2013 10:01:14 -0800, Jon Perryman wrote: >FBS and VBS work the same as FB and VB except for records spanning into the >next block. They all ignore track size. > The S in FBS denotes Standard, not Spanned. In an FBS data set, all blocks except possibly the last are identical in size. There is a needless constraint that you are not allowed to MOD to an FBS data set. Inadequate access methods. UNIX uses FBA with standard block sizes, and append works fine.
How can an access method "ignore" track size? An attempt to write a block larger than (the space remaing on) a track is bound to fail. >In all my years, I've only seen VBS used once (I think it is SMF data). The >biggest advantage for VBS was that the size for all physical records except >the last would be the blocksize. If you specified blocksize 32760, then each >track would contain one physical record of 32760 bytes and the rest of the >track. To make it optimal, you specified a blocksize of half a track. > I believe IEBCOPY uses VBS. And I believe one of the motivations for VBS was the requirements of FORTRAN, which wrote logical records larger than DASD tracks of its era. Binder is able to use BLKSIZE=32760 efficiently. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
