Barbara Nitz wrote on 09/26/2005 07:13:24 AM: > > >Some have suggested that we add an option to WHERE, > >filtering based on data type. The most common filter that has been > >proposed is a MODULE data type filter. It would be interesting to hear > >opinions on this suggestion from regular IBM-MAIN contributers > > I am not sure I understand what is proposed here. What would a module data > type filter do to WHERE (or systrace)? >
The key to understanding why a module filter has been proposed is that WHERE produces a report describing multiple things containing a byte, but it only returns a single "best fit" result via symbol X (or the WHERE service parameter list). A MODULE data type filter would tell WHERE that the invoker of the service or the subcommand was only interested in modules containing the byte of interest. If you had the option in effect and pointed WHERE at offset 0 in the CVT, the single piece of information returned via symbol X (or the WHERE service parameter list) would name the nucleus CSECT containing the byte instead of returning a description of STRUCTURE(CVT) whose origin would yield a better fit. The origin of the CSECT is a few bytes lower than offeset 0 in the CVT to accomodate the CVT prefix. In common parlance symbol X (and the WHERE service parameter list) do the following: 1. Unqualified questioners get the best available answer to "What named AREA, MODULE, or STRUCTURE contains that byte?" 2. Questioners asking about modules would only get X set if a module contained the byte. As you and others have described what you'd like SYSTRACE to do, SYSTRACE would use module filtering in its calls to the WHERE service routine because it would want answers pertaining to modules and would not be interested in answers pertaining to AREAs or STRUCTUREs. Bob Wright - z/OS MVS Service Aids ---------------------------------------------------------------------- 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
