I wonder - Why is it not possible to add records to the beginning of a data set? Wouldn't it be possible for a sufficiently clever program to place the inserted records into a newly allocated area on disk, and then modify the VTOC to point to that new area first and the old first area next? It might require rewriting a bunch of control blocks, and probably wouldn't work for some kinds of data sets (FBS comes to mind), but isn't it theoretically possible?
-- Jack Hamilton Management Information & Analysis - Analytic Information Services Kaiser Foundation Health Plan, Inc. 1950 Franklin Street, Oakland, California 94612 +1 510 987-1556 (KP tieline 8-427-1556) NOTE: This email document and attachments are covered by CA Evidence Code §1157 and CA Health and Safety Code §1370. NOTICE TO RECIPIENT: If you are not the intended recipient of this e-mail, you are prohibited from sharing, copying, or otherwise using or disclosing its contents. If you have received this e-mail in error, please notify the sender immediately by reply e-mail and permanently delete this e-mail and any attachments without reading, forwarding or saving them. Thank you. IBM Mainframe Discussion List <[email protected]> wrote on 10/16/2008 12:24:56 PM: > On Thu, 16 Oct 2008 13:53:47 +0200, Hunkeler Peter (KIUK 3) > <[EMAIL PROTECTED]> wrote: > >>I have a requirement to insert some records in the beginning of a file > >>where already some lines are existing . i tried using DISKW using > MOD, > >>but they are appending to the end. How do we insert in the > beginning? > >>I am using REXX for this program. > > > >There is no direct way to insert data into a sequential data set, > >neither > >at the beginning nor inbetween. You need to re-write the dataset with > >all > >the new and current records in the desired sequence. > >... > Peter came close to saying this, but I think it's worth highlighting. > This "restriction" has nothing to do with REXX; it's just the way > processing of sequential datasets works. > Regarding MOD, last I checked there was no MOD option to EXECIO > (and I wouldn't expect it there) so I assume the origonal poster > was refering to DISP=MOD or MOD on a TSO ALLOCATE command. > In those contexts MOD implies "Add to the end of a dataset". > In the JCL manual it clearly states that MOD implies either > The data set exists and records are to be added to the end of it. > The data set must be sequential. > or > A new data set is to be created. > > HELP for the ALLOCATE command is a lot less clear: > ADDITIONS ARE TO BE MADE TO DATA SET > > Pat O'Keefe > ---------------------------------------------------------------------- > 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 ---------------------------------------------------------------------- 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
