> But your first post said you didn't want use the TIOT? Sorry. My first post was badly phrased. I didn't mean that. I said
My preference would be for something low overhead (I have a bunch of DD's to look up) and that did not require below the line storage (such as searching the TIOT and using SWAREQ to get the JFCB). and you can read that either way. I meant I wanted a method -- such as TIOT/SWAREQ -- that did not require BTL storage. At the time, I was not aware of a TIOT or JFCB field that would indicate DUMMY, but I wanted something "such as" that. I think I'm going to write an assembler routine DD and concatenation number in, JFCB and DUMMY bool out, via SWAREQ. There is undoubtedly stuff in the JFCB that will come in handy also such as DISP. bool moreConcats = GETJFCB(const char ddname[9], const int concatNum, jfcb *jfcbPtr, bool &isDummy); I'll do the check for DUMMY in the assembler routine and return a bool so that (1) I can do a quick CLC for NULLFILE and (2) this *slightly* kludgey logic is in the assembler code, not in every caller's code. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Gerhard Postpischil Sent: Friday, February 12, 2010 11:35 AM To: [email protected] Subject: Re: Determining if DUMMY allocation On 2/12/2010 2:04 PM, Charles Mills wrote: > I'm not so desperate for ultra performance that I would use any field that > was likely to not provide a reliable answer under certain circumstances. > > It's "product" code that will be shipped to multiple customers, many of > which will have MVS environments under which I will not be able to test, > such as JES3. Unless you are getting control during step allocation (possible SMF or similar exit), a zero UCB address is reliable. No need for the JFCB, as you can test the status bits. A DUMMY won't have the SYSIN, SYSOUT, or similar flags. I've used this method for more than forty years with no problems. But your first post said you didn't want use the TIOT? Gerhard Postpischil Bradford, VT ---------------------------------------------------------------------- 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
