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Question on Abend Analysis and Compiler Listing...


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cybertaurean

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Joined: 22 Dec 2008
Posts: 87
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PostPosted: Wed Apr 21, 2010 11:45 am
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Hi All,

Given below is a typical abend message -

+IDI0002I Module XXXXXXXX, program XXXXXXXX, offset X'EA4': Abend UXXXX (I believe this is the memory location that points to the section of code that was active. Is there concept like IP - Instruction Pointer, Frame Pointer, Stack Pointer etc. in mainframe?. Let me know if there is any documentation available on this. I am trying to relate it with Base in Windows which is usually 0X40000000).

In case we don't have the listing available for the code ABC, can I convert the offset to a location in the compiler listing, ABC.LST for the module (I can get the LST file from CHGMAN).

The abend UXXXX could happen at multiple locations in the module. This would help me know where it happened (I'm not sure about this statement since the X'EA4' shown would be the location where the abend routine got executed. This would not be sufficient to know from which part of the code and under what condition, the abend routine was called).

Bottomline, Is there any way to analyze in case there is no LISTING available for the module?.

Regards,
Sumesh
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Robert Sample

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Joined: 06 Jun 2008
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PostPosted: Wed Apr 21, 2010 4:33 pm
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You need to learn the concept of PSW (Program Status Word) and the fields within it. You also need to go to www.redbooks.ibm.com and find manual SG24-7110, z/OS Diagnostic Data Collection and Analysis and read this manual.

It may be possible to debug the program without a listing but the listing makes it much easier.
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cybertaurean

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Joined: 22 Dec 2008
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PostPosted: Wed Apr 21, 2010 7:12 pm
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Thanks a lot Robert!!!. I got the book. Will try to learn it icon_smile.gif.
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William Thompson

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Joined: 18 Nov 2006
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PostPosted: Wed Apr 21, 2010 7:21 pm
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Robert Sample wrote:
It may be possible to debug the program without a listing but the listing makes it much easier.
A dump and just backtracking from the abend point can reveal the source of the bad data, BTDT...grin.....
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cybertaurean

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PostPosted: Thu Apr 22, 2010 10:03 am
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Hi William,

I didn't quite understand what you were trying to convey (guess I didn't catch the lighter side of it icon_smile.gif ). Could you let me know how it is possible to backtrack the flow ?

Prog A

if A
else
call abend_routine

if B
else
call abend_routine

if C
else
call abend_routine
.
.
.


abend_routine (could be an assembler piece as shown below) -
PRGDUMP CSECT
SAVE (14,12)
BALR 11,0
USING *,11
ABEND XXXX,DUMP
END

In the above module, if we don't have compiler listing, it would just show the offset in prog A where the PRGDUMP got called?.

Now, with the data above, how can we know where exactly the call came from (backtracking) without the listing available?

Regards,
Sumesh
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Kjeld

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Joined: 15 Dec 2009
Posts: 365
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PostPosted: Thu Apr 22, 2010 12:01 pm
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In Sumesh's example, I will find it hard to do without a listing. You can do it by location the working storage data involved in the abended instruction.

But, if it is a programmed (intentional) abend, the programmer should have documented the condition and data that lead to the decision to abend the programme.
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enrico-sorichetti

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Joined: 14 Mar 2007
Posts: 10886
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PostPosted: Thu Apr 22, 2010 12:17 pm
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Quote:
In case we don't have the listing available for the code ABC, can I convert the offset to a location in the compiler listing, ABC.LST for the module (I can get the LST file from CHGMAN).


just take a decision!
You have a listing or not ?
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enrico-sorichetti

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PostPosted: Thu Apr 22, 2010 12:43 pm
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Quote:
The abend UXXXX could happen at multiple locations in the module.


a user abend should describe an abnormal situation,
irrelevant of where in the program the issue has been discovered

if the meaning is different depending on the location where the abend was issued,
then that' s a serious programming/logic mistake
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dick scherrer

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PostPosted: Thu Apr 22, 2010 7:23 pm
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Hello,

If there are 3 different situations that could cause a user abend, there should be 3 different user abend values. . .

If there are 3 different situations that are permitted to cause the same user abend then there should be an additional working-storage entry that contains the information as to why the abend was caused. Before the ws entry that describes the abend, it helps to add an "eyecatcher" so that when looking at a dump, something "readable" is always there.
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cybertaurean

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Joined: 22 Dec 2008
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PostPosted: Thu Apr 22, 2010 9:30 pm
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Thanks everyone for the replies :-)

@enrico

The listing I referred to is the LST file that is interpreted through CHGMAN. I think this gets created even if you havent provided LIST in Compile Option (not sure).

What I meant by "no listing" is that, since the module was not compiled with LST option, I will not have a listing for the particular module when it abends.

@dick

that should ideally be the case to understand based on any indicator set according to the location from which the abend routine was called. Unfortunately, this is not the case for me.

However, say I had an code C that would be 1, 2 or 3 according to the location, how will I know what is in C if I dont have a listing for the module at all?.

Regards,
Sumesh
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enrico-sorichetti

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PostPosted: Thu Apr 22, 2010 9:41 pm
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We are just wasting time here!
if a Compiler and Linkage editor listings are not available
the chances for a reasonable debugging are close to 0

review You organization practices in order to have the proper info available at all time.

Furthermore if compile and linkage editor listing are not available Your organization
might not pass any reasonable audit ( seen it, done it )
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William Thompson

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Joined: 18 Nov 2006
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PostPosted: Thu Apr 22, 2010 9:52 pm
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cybertaurean wrote:
Prog A

if A
else
call abend_routine

if B
else
call abend_routine

if C
else
call abend_routine
.
.
.


abend_routine (could be an assembler piece as shown below) -
Code:
PRGDUMP  CSECT         
         SAVE  (14,12) 
         BALR  11,0     
         USING *,11     
         ABEND XXXX,DUMP
         END           

Based upon your example:
The CALL should be a BALR 14,15 so look at R14 for the call.
You may need to look at the savearea pointed to by R13 to get R14.
Look backwards in the dump until you find the CLC/CLI followed by a BNE to the CALL.
Look backwards to find where the CLC/CLI got the objects for the compare, one should point to the 88 value of A or B or C and the other should point to the actual WS data area of the unknown.
The 88 value should tell you which IF did the CALL and the WS data will tell you why it failed the compare.
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dick scherrer

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Joined: 23 Nov 2006
Posts: 19243
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PostPosted: Thu Apr 22, 2010 10:04 pm
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Hello,

Quote:
Unfortunately, this is not the case for me.
Suggest this become the case. . . It is a matter of self-preservation icon_smile.gif

Quote:
how will I know what is in C if I dont have a listing for the module at all?.
If you have neither listing nor "eyecatcher", finding what is in "C" may be most difficult - if it is possible at all. . .
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cybertaurean

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Joined: 22 Dec 2008
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PostPosted: Fri Apr 23, 2010 10:06 am
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Thanks everyone for the replies...

@enrico
The audit passed is the reason why the module is live. I guess we will have to reinstall using LIST option icon_smile.gif.

@william
I got a long way to go to reach your expertise icon_smile.gif. Guess, I will have to study assemblers now. However, is that enough?. Will I have to learn the architecture, addressing etc. besides learning assembler?

@dick
I had a walkthrough of the code and found that I am not completely lost here. I happened to find two values ABEND-PARAGRAPH and ABEND-STATUS. I located the BLW's for these fields and searched the hex-dump in Fault Analyzer and VOILA!!! I got the values. The abend was due to a missing segment (will analyze further to find the reason why this segment was not present;that's another story).

Bottomline is that I'm quite happy that I decided to stretch a bit and subsequently learned more.

Regards,
Sumesh
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dick scherrer

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Joined: 23 Nov 2006
Posts: 19243
Location: Inside the Matrix

PostPosted: Fri Apr 23, 2010 7:14 pm
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Good to hear you found the problem icon_smile.gif

Quote:
I happened to find two values ABEND-PARAGRAPH and ABEND-STATUS.
Yup, a paragraph-name should certainly "catch the eye" icon_wink.gif

Thank you for posting what you found,

d
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