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Use of PL/I TCA in LE Enviornment

 
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Vasu Rajagopalan

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Joined: 12 Jul 2011
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Location: India

PostPosted: Sat Apr 28, 2012 5:22 pm    Post subject: Use of PL/I TCA in LE Enviornment
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I have some assembler programs which put "hooks" in the PLI programs by modifying the following hex offsets of the PL/I TCA so that the assembler program can trace storage allocation and module flow

X'48 of TCA to get address of PL/I overflow routine for getting VDA
X'6C' of TCA to get address of PL/I dynamic storage
X'F0' of TCA to get address PL/I flow routine .
X'74' of TCA for overflow routine for getting DSA..

These offsets were based on on old PL/I compiler. With Enterprise PL/I compiler which conforms to LE, these offsets are no longer valid .. The "hooks" no longer work ..

My questions are
a) How to find equivalent PL/I TCA offset under LE ?..
b) Are we better off by redesigning this assembler to use LE based services instead of playing with PL/I TCA offsets ..
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Bill O'Boyle

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PostPosted: Sat Apr 28, 2012 7:05 pm    Post subject: Reply to: Use of PL/I TCA in LE Enviornment
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I believe choice b) would be wiser. Traversing control blocks, using IBM defined DSECT's, should only require a re-assembly/link of the Assembler program if there were DSECT changes.

Control block traversing in a high-level language, such as PL/I or COBOL, using undocumented methods, can be risky (as you've found out), so use Assembler and you'll be OK as long as it's supported by IBM. However, I don't think you'll need to use LE Callable routines to accomplish this. If so, you'd have to make the Assembler program fully LE-compiliant or using "CEEPIPI" (non-CICS) for temporary compliance, which in both cases, is more of a PITA than anything. icon_wink.gif

The TCA DSECT should be the same, regardless of the language. But, I could be wrong as PL/I does some funny stuff under the covers. icon_eek.gif

Waiting for Prino. icon_wink.gif

HTH....
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Vasu Rajagopalan

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PostPosted: Sat Apr 28, 2012 8:06 pm    Post subject:
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Bill, thanks for your quick response.. I really do not know which IBM defined DSECT to use for these. I went through MVS data area manuals and , I could not figure out .. Will keep looking though ..
Problem is these assembler programs query the save area chain , change the the PL/I environment for the called PL/I main based on these TCA offsets, write a trace record for storage allocation and module flow . and continue with passing control to PLI main routine Since storage allocation has become common under LE ( not language specific ) using these PLI specific TCA will not work .. Since I do not have code this, but suggest a design approach icon_cool.gif , I thought I would suggest RPTSTG option in my design document for tracing storage allocation ..
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Bill Woodger

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PostPosted: Sat Apr 28, 2012 8:29 pm    Post subject: Reply to: Use of PL/I TCA in LE Enviornment
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This is a debugging/development assistance thing? Or what?
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Bill O'Boyle

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PostPosted: Sat Apr 28, 2012 8:34 pm    Post subject: Reply to: Use of PL/I TCA in LE Enviornment
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Here's some excerpt code to get you started. R1 and R2 can be substituted for whatever registers you decide to use -

Code:

         CVT   DSECT=YES,LIST=YES      CVT-DSECT (PREFIX=NO)           
         IKJTCB                        TCB-DSECT
IEFTIOT1 IEFTIOT1                      TIOT-DSECT
         IHAACEE                       ACEE-DSECT
         IHAASXB                       ASXB-DSECT
         IHAASCB                       ASCB-DSECT
*
         L     R1,CVTPTR               CVT-ADDRESS   
         L     R2,0(,R1)               ADDRESS OF TCB POINTERS
         LR    R1,R2                   SAME
         L     R1,4(,R1)               TCB-ADDRESS
         ST    R1,ADDRTCB              STORE IN FWORD (SAFEKEEPING)
         L     R1,TCBTIO-TCB(,R1)      LOAD TIOT-ADDRESS
         ST    R1,ADDRTIOT             STORE IN FWORD (SAFEKEEPING)
***********************************************************************
*        GET THE 'USERID', 'JOB-NAME' AND 'JOB-NUMBER' VIA CONTROL    *
*        BLOCK TRAVERSING.                                            *
***********************************************************************
         L     R2,12(,R2)              POINT TO 'ASCB'
         ST    R2,ADDRASCB             STORE IN FWORD (SAFEKEEPING)
         L     R2,ASCBASXB-ASCB(,R2)   CHAIN TO 'ASXB' ADDRESS
         ST    R2,ADDRASXB             STORE IN FWORD (SAFEKEEPING)
         L     R2,ASXBSENV-ASXB(,R2)   CHAIN TO 'ACEE' ADDRESS
         ST    R2,ADDRACEE             STORE IN FWORD (SAFEKEEPING)
         MVC   USERID,ACEEUSRI-ACEE(R2) POPULATE 'USERID'
         L     R2,ADDRTIOT             LOAD 'TIOT' ADDRESS
         MVC   JOBNAME,0(R2)           POPULATE 'JOB-NAME'
         L     R2,540                  CURRENT 'TCB'
         L     R2,180(,R2)             POINT TO 'JFCB'
         L     R2,316(,R2)             POINT TO 'SSID'
         LA    R2,12(,R2)              OK, WE'RE HERE
         MVC   JOBNBR,0(R2)            POPULATE AS C'JOB00000'

This may not be what you exactly need, but it can get you on your way.

HTH....
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Vasu Rajagopalan

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PostPosted: Sun Apr 29, 2012 7:22 am    Post subject: Reply to: Use of PL/I TCA in LE Enviornment
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Thank you Bill. I think what you showed me help me to get further on my way .. Thanks once again ..
To answer, Mr Woodger's question , what I am maintaining is an old PL/I based IMS application which had a debug/trace feature implemented using Assembler. This trace function stopped working after the application moved to LE environment .. ( that is, Enterprise PL/I compiler )

Regards,
Vasu
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Bill O'Boyle

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PostPosted: Sun Apr 29, 2012 7:40 am    Post subject: Reply to: Use of PL/I TCA in LE Enviornment
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BTW, welcome to the forum. We offer our services free of charge and if you post within the rules of the forum, you'll be assisted when a member can spare some of his/her time.

However, we do encourage that a poster attempts to find the answer to his/her question before posting. It will show other members that you've tried to find an answer or, the answer with which you've found is a little confusing or requires additional explanation..

Regards,
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Nic Clouston

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PostPosted: Sun Apr 29, 2012 2:22 pm    Post subject:
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Do you actually need this "feature"? There must be hundreds of thousands of PL/1 IMS programs in the world that do not have this and yet they are maintained and debugged successfully.
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Vasu Rajagopalan

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PostPosted: Mon Apr 30, 2012 6:57 am    Post subject:
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I agree with you, Nic. But, I cannot make that call. I will inform the customer about this . Just wanted to get a opinion from the experts, since I could not see a solution (by continuing to use PL/I's TCA for tracing ) based on my own knowledge, walking through the assembly code, reading through manuals..

Regards,
Vasu
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