On 30 Oct 2007 13:46:07 -0700, in bit.listserv.ibm-main you wrote: >On Tue, 30 Oct 2007 13:29:54 -0500, Dave Kopischke wrote: > >>On Tue, 30 Oct 2007 09:46:36 -0600, Howard Brazee wrote: >> >>>But why should a program care about block size? >> >>Funny you should ask this; We had a major project implement a couple weeks >>ago. To deal with the number of object moves, many of the libraries were just >>cloned and renamed at implementation time. During this, a couple pretty >>important PDS's were reblocked. A pretty benign change from my point of view. >> >>It turns out a program update process allocates one of these PDS's >>SHR,BLKSIZE=3200. This effectively reblocked the PDS. Every member in this >>PDS that was longer than about 40 lines was corrupted and innaccessible. >> >>That's a reason to care, but probably not the point trying to be made. There >>are code bombs waiting to explode. Even a seemingly benign change can >>trigger one. >> >Ah, but if the programmer hadn't coded BLKSIZE in the DCB but >left it zero and accepted whatever value was in the data set >label, the problem would never have occurred. The problem was >caused by the programmer's delusion that he needed to override >BLKSIZE. And if the OS, according to my idea, had not updated >the BLKSIZE, the data set would not have been corrupted.
All you have to do to foul the works is forget to code BLOCK 0 or use SYNCSORT with certain input VSAM data sets which it assumes are RECFM = F or V depending and things go downhill from there. > >-- gil > Clark Morris ---------------------------------------------------------------------- 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
