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BLW cannot be found in the abend dump


IBM Mainframe Forums -> ABENDS & Debugging
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rohitsapru

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Joined: 20 Jul 2006
Posts: 2
Location: India

PostPosted: Wed Aug 03, 2011 6:30 pm
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Hi people! I have a question regarding dump analysis.

For some of the abends that I am checking at my site, the BLW (base locator for working storage) cannot be found in the dump.

We have IBM Fault Analyzer at our shop, however I think this question may not be directly related to the product (I could be wrong though!). The way I see it, the 'fault' captured by FAZ is just a user-friendly representation of CEEDUMP, and other information.

The fault does contain the following information. But when I search for that particular BLW, or the address for that BLW, it is not present.

Recently referenced data items:
Data Item . . . . . . . . : BLW=NNNN+MMMM
At Address. . . . . . . : PPPPPPPP
Length. . . . . . . . . : something
Data Item Storage . . . : something

I used to think that the fault/dump should capture ALL BLWs (and BLLs and BLFs). Is this understanding incorrect? icon_smile.gif

Thank you.
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Bill O'Boyle

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Joined: 14 Jan 2008
Posts: 2501
Location: Atlanta, Georgia, USA

PostPosted: Wed Aug 03, 2011 7:58 pm
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If you subtract the ILC (Instruction Length Code) from the PSW, it should take you to the address of the bad instruction.

The PSW displays the address of the NSI (Next Sequential Instruction).

I can't help you with FAZ.... icon_wink.gif

Bill
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Bill Woodger

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Joined: 09 Mar 2011
Posts: 7309
Location: Inside the Matrix

PostPosted: Wed Aug 03, 2011 8:11 pm
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rohitsapru wrote:
[...] I have a question regarding dump analysis.

For some of the abends that I am checking at my site, the BLW (base locator for working storage) cannot be found in the dump.

[...]


You can locate all the locators, for certain, in their allocated place in your Cobol object code.

You show an example of "Recently referenced data items" - what happens if there are none (whatever "recent" means in that context, or "referenced" for that matter).

So, they are in the dump (in that they have storage assigned to them and will have some value in them).

If they are not in some particular formatted extract from the dump, that is a different question. You are in a better position to research that than I am.
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Robert Sample

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Joined: 06 Jun 2008
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Location: Dubuque, Iowa, USA

PostPosted: Wed Aug 03, 2011 8:36 pm
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Quote:
I used to think that the fault/dump should capture ALL BLWs (and BLLs and BLFs). Is this understanding incorrect?
Your understanding is incomplete. An abend and consequent dump may be generated by the application program or a system routine. If the application program causes the abend, LE (Language Environment) may intercept that abend and format its own dump for the abend. In this case, you may or may not get all the data you would get from a full system dump.
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rohitsapru

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Joined: 20 Jul 2006
Posts: 2
Location: India

PostPosted: Wed Aug 03, 2011 10:07 pm
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Thank you for your replies.

Locating the bad instruction in the abend is almost always a clear and simple task.
Searching for the Locators in the COBOL object code is also straight forward.

For some reason, I was unable to locate certain storage areas in the formatted dump.
Ummm, I need to dig my head deeper and make an honest attempt to find out why!
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Bill Woodger

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Joined: 09 Mar 2011
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PostPosted: Thu Aug 04, 2011 4:32 am
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Good for you, Rohit.

Do try the manual for the product. It should (I hope) define terms such that you know what to expect in which circumstance, when to expect nothing, etc.

As you are probably aware, it is possible to "accidently" trash the contents of all your BLx's, save areas and other vital stuff. Anything formatting the dump relies on this sort of information being valid, so will produce non-standard output. What you posted so far doesn't look to me like that yet, but you may have other clues. Like anything, a dump formatter relies on the quality of the input data. Garbage in, Garbage Out.
It is good to be able to know your way around the "nak***" dump in such situations :-)
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nevilh

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Joined: 01 Sep 2006
Posts: 262

PostPosted: Thu Aug 04, 2011 4:11 pm
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If you want to test to see if it is the Fault Analyzer that is causing the problem rerun the job but add a DD card that looks like the following
//IDIOFF DD DUMMY
This will disable the fault analyzer for this job. Just make sure you have a
SYSUDUMP or SYSABEND dd card in the JCL
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