Jay Maynard wrote: > > The limit is that the cylinder number is a halfword, and exceeding that > breaks a LOT of things. There are even today things you can't put on a > 3390-9 beyond cylinder 65535 (the JES2 spool dataset springs immediately to > mind).
Minor nit. On MVS a single extent cannot exceed 65535 *tracks* and a 3390-9 has 10017 cylinders (150255 trks). Theoretically, ckd architecture can support 65535 cyls, 65535 heads (or trks/cyl), 255 blks/trk, each blk with a 255 byte key area and a 65535 byte data area (which adds up to a fairly large number). Greg
