Bill, >From my little knowledge about VTOC what you said is totally correct.
Can I ask one quick silly questions? I noticed that both format 1 and format 3 DSCBs use 'lower limit' and 'upper limit' to describe the scope of each extent and they're all in CCHH format, not CCHHR as I assumed. Does that mean all data sets in z/os will consist of complete tracks? So a track is the smallest unit we can allocate to a data set. We cannot, say, allocate a half of a track to one data set and the left to another one. (I know we can allocate space in other units such as BLKS, KB, RECORDS... but I guess they'll be rounded to tracks or cylinders by system at end) But I'm not sure because I once read from the manual about VTOC: A VTOC consists of complete tracks. If that is true for all data sets, why the manual took the trouble to tell me again? However, if it's not true, how can you find the start of a data set by CCHH? Thanks. On 9/13/07, (IBM Mainframe Discussion List) <[EMAIL PROTECTED]> wrote: > > > 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 > > > > -- Best Regards, Johnny Luo ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
