No parm in JCL results in a parmfield with a lenghtfield of zeros. L R3,0(R1) ADDRESS OF PARM. LH R2,0(R3) LENGTH OF PARM. LTR R2,R2 LENGTH ZERO? BZ END ==> NO PARM.
Kees. "Thomas Berg" <thomas.b...@swedbank.se> wrote in message news:<e46b4df55a5e8746855078ae31f1b180336f71d...@fspas01ev010.fspa.myntet.se>... > There is of course a problem if You have a program that: > 1. Expects parm from both the JCL PARM mechanism and from > common standard linkage/calls, > and > 2. Receives a parm with a length field value of exactly 100, > and > 3. Can't determine if the parm in reality is longer than > that or not (that is: if coming from JCL). > and > 4. The calling is not through JCL PARM, > and > 5. The calling part is not aware of this new possible format. > > The question is of course if this situation is a big problem > in practice. Someone with knowledge has to evaluate that. > > > BTW, when You omit the JCL PARM, what does the program receive ? > A length field with value zero only ? What type of area is placed > immediately after the length field in this case ? > > > > Regards, > Thomas Berg > __________________________________________ > Thomas Berg Specialist IT-U SWEDBANK > > > > > > > -----Ursprungligt meddelande----- > > Från: IBM Mainframe Discussion List > > [mailto:ibm-m...@bama.ua.edu] För Vernooij, CP - SPLXM > > Skickat: den 29 oktober 2009 11:52 > > Till: IBM-MAIN@bama.ua.edu > > Ämne: Re: A modest PARM proposal > > > > Don't think it is that simple. > > I know how the parmfield works today. > > If I understand the proposed new parmfield correctly, > > > > > Today: lengthfield + parm (max 100 bytes) > > > > > Tomorrow: lengthfield + parm (max 100 bytes) + padding to 102 > > the first 102 bytes will remain unchanged and additional > > parms will be appended to it. This means the first length > > field will never be more than 100. > > How can a program determine if the data in bytes 101 and > > further are part of the new parmlayout and contain the > > lengthfield of the remainder of the parm OR it is data not > > related to the parm. In the last case, referencing data after > > byte 100 can even result in an 0C4 abend. > > > > Kees. > > > > > > "Graeme Gibson" <gra...@ase.com.au> wrote in message > > news:<20091029111112.3a5761c...@mail.ase.com.au>... > > > >How can new programs determine if they received the new or the old > > > >format, i.o.w. if they can/should process the data after > > byte 100 or > > not? > > > > > > It's really quite simple Kees, the program should process > > exactly the > > > number of bytes that the 2-byte (halfword) length prefix says is > > > present, no more and no less. This has been the case for > > > 40 years. > > > > > > Running a program in batch that lets me dump storage: > > > > > > //STEP1 EXEC PGM=DBUG,PARM='TP,L,HC,PA=(ABCDEFGH)' > > > > > > here's what R1 -> at the time the program receives control: > > > > > > L R1$ 128 /* list what R1 points at for 128 bytes > > > 00006FE0(+000) 80006FE6 00000015 E3D76BD3 6BC8C36B > > |::?W::::TP,L,HC,| > > > 00006FF0(+010) D7C17E4D C1C2C3C4 C5C6C7C8 5D000000 > > |PA=(ABCDEFGH):::| > > > 00007000(+020) 00000000 00000000 00000000 00000000 > > |::::::::::::::::| > > > 00007010(+030) 00000000 00000000 00000000 00000000 > > |::::::::::::::::| > > > > > > Breaking it up a bit to make it clearer: > > > > > > 006FE0 80006FE6 /* the parmlist (with end-of-list bit ON) -> > > > 006FE6 0015 /* the length prefix part of the parameter > > > 006FE8 E3D76BD3 6BC8C36B D7C17E4D C1C2C3C4 C5C6C7C8 5D00 /* the > > > string part in hex > > > T P , L , H C , P A = ( A B C D E F G H ) > > /* ..and > > > in characters > > > > > > Now, there's NO padding out of the string buffer to 100 characters > > > with blanks. So, what are those "broken" programs making > > of all those > > > x'00' bytes that follow the actual PARM= value? Countless existing > > > programs may well be moving an arbitrary 100 or 102 bytes > > of parameter > > > to their own buffer/work area, but it seems clear that those same > > > programs must be taking notice of the length prefix when it > > comes to > > > parsing the string. Or perhaps they all regard an x'00' > > > as indicating end of PARM= string! But then I'm not aware of any > > > commitment by IBM to ensure that the PARM= string is even > > filled out > > > with x'00' bytes. > > > > > > So, assuming the CI/SWA/Initiator support for PARM= was enhanced to > > > allow PARM= strings up to 32767 (x'7fff') characters. > > Presumably the > > > Initiator would continue, as it does now, to place the > > PARM= parameter > > > in a storage area big enough to hold the maximum size it can be, ie > > > 32767+2 bytes (instead of 102 bytes as at present). Nothing would > > > change for those existing (strictly > > > "broken") programs that are copying an arbitrary 100 (or > > 20, or some > > > other number?) bytes of data into their own work areas. > > > > > > Of course, if a person using that program changed the PARM= > > string to > > > be longer than 100 characters, then all bets are off. > > > > > > The best outcome would be a message; like "I'm sorry Dave, but I > > > thought you knew that I can't handle a PARM string of more than 100 > > > characters. Report to the airlock immediately". > > > > > > An abend would be ok too. > > > > > > Just continuing to execute with possibly unknown results > > would be the > > > worst outcome. > > > > > > I suspect that there are programs in existence which cannot accept > > > even 20 characters of PARM= data, because the programmer > > assumed there > > > would only be, say, an 8 digit date (yyyymmdd), or some > > other tiddly > > > bit of data in the PARM= field. > > > > > > > > > Ok, it's nearly Christmas / Hannuka / Pagan Pissup (ie. > > drinking) time > > > again, so take care all. > > > Graeme. > > > > > > > > > At 02:47 AM 29/10/2009, you wrote: > > > >How can new programs determine if they received the new or the old > > > >format, i.o.w. if they can/should process the data after > > byte 100 or > > not? > > > > > > > >Kees. > > > > > > > > > > > >"Thomas Berg" <thomas.b...@swedbank.se> wrote in message > > > > > Today: lengthfield + parm (max 100 bytes) > > > > > Tomorrow: lengthfield + parm (max 100 bytes) + padding to 102 > > > > bytes + newlengthfield + newparm (max 4GiB ? :) ) > > > > > > > > > > This of course has the limitation means that the receiving part > > > > has to add 102 to get the long parm. > > > > > But it will only affect new programs that need to handle more > > > > that 100 bytes parms, I think ? > > > > > > > > ---------------------------------------------------------------------- > > > For IBM-MAIN subscribe / signoff / archive access > > instructions, send > > > email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO > > > Search the archives at http://bama.ua.edu/archives/ibm-main.html > > ********************************************************************** > > For information, services and offers, please visit our web site: > > http://www.klm.com. 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