COBOL DB2 Load Modules Comparison

sudmax · New User Joined: 28 Nov 2010 Posts: 3 Location: thailand

I am using File Manager to compare COBOL-DB2(no SQL statements) Load modules, although there are some differences in both the loads in working-storage the utility return as "Matched".

The same source when compiled with IGYCRCTL directly without going thru pre compilation step, the differences are captured and the tool says "Load module don't match".

Is there any specific way to compare COBOL-DB2 loads where it can report the differences.

Bill Woodger · Posted: Tue May 15, 2012 2:15 pm

What are you trying to achieve?

sudmax · New User Joined: 28 Nov 2010 Posts: 3 Location: thailand

Hi I tried to compare COBOL load module by IBM file manager that the result of comparison should be "didn't matched" by we "Compile date" and "Link date and time" . The below is my JCL for compare

//FILEMGR EXEC PGM=FMNMAIN
//STEPLIB DD DISP=SHR,DSN=SYS1.IFM.LINKLIB
//SYSPRINT DD SYSOUT=*
//FMNTSPRT DD SYSOUT=*
//SYSTERM DD SYSOUT=*
//SYSIN DD *
$$FILEM CLM ,
$$FILEM CMPLVL=CSECT,
$$FILEM LMODC=(ADDR,SIZE,MODE,LINK,ATTR,AC),
$$FILEM CSECTC=(ADDR,SIZE,MODE,COMP,IDRZAP,TEXT),
$$FILEM LIST=DELTA,
$$FILEM WIDE=YES,
$$FILEM HILIGHT=YES,
$$FILEM NUMDIFF=ALL,
$$FILEM DSNOLD=MY.LOADLIB1(X1),
$$FILEM DSNNEW=MY.LOADLIB2(X2)

sudmax · New User Joined: 28 Nov 2010 Posts: 3 Location: thailand

Sorry I provide the wrong JCL. We use below option

$$FILEM CLM ,
$$FILEM CMPLVL=CSECT,
$$FILEM LMODC=(ADDR,SIZE,MODE,LINK,ATTR,AC),
$$FILEM CSECTC=(ADDR,SIZE,MODE,COMP),
$$FILEM LIST=DELTA,
$$FILEM WIDE=YES,
$$FILEM HILIGHT=YES,
$$FILEM NUMDIFF=ALL,
$$FILEM DSNOLD=MY.LOADLIB1(X1),
$$FILEM DSNNEW=MY.LOADLIB2(X2)

Bill Woodger · Posted: Tue May 15, 2012 2:58 pm

sanaanil · New User Joined: 14 Apr 2005 Posts: 5 Location: Bangalore

Hi Bill,

We have referred the manuals for the various options as mentioned. Let me give you a glimpse of the situation.

Example
----------
PROGA
---------
WORKING-STORAGE
01 ABCD PIC X(3).

PROGB
--------
WORKING-STORAGE
01 ABCD PIC X(6).

Compiled the bove two programs using Enterprise COBOL v 4.1, when comparing the load modules, ideally they shouldn't match, but to the surprise the tool says "Matched".

However, if the same programs are compiled using COBOL for VM MVS v 2.x compiler, the tools reports as not matched (compiler options used are same as used for above).

I would like to know, if there are any specific compiler options for Enterprise COBOL v 4.1 which will enable to report the differences.

dbzTHEdinosauer · Posted: Tue May 15, 2012 10:24 pm

WTF does this mean?

Nic Clouston · Posted: Tue May 15, 2012 10:31 pm

dick scherrer · Posted: Tue May 15, 2012 11:27 pm

Hello,

Suggest you look at the compiler output listing at that point and see what is different.

I suspect that there is no difference in the working-storage load module because some left-over space was used.

Try changing the field from 3 to 300000 and then compare (or look at the listings).

Suggest you also refrain from posting the same question on multiple forums. . .

Bill Woodger · Posted: Wed May 16, 2012 4:12 am

dbzTHEdinosauer · Posted: Wed May 16, 2012 4:41 am

why do you not use the load module attributes presented by AMBLIST
and compare those?
epecially since you don't appear qualified to properly parameterize a compare thru file-aid?

Bill Woodger · Posted: Wed May 16, 2012 4:51 am

I'm curious about what you are trying to achieve. If you don't want to compare the executable code (which would be different for different-sized fields) you have to think much more about how to make the Working-Storage reliably mismatch. No chance with any Linkage Section changes, without going to the code. So what is your aim?

sanaanil · New User Joined: 14 Apr 2005 Posts: 5 Location: Bangalore

Hi Bill,

Thanks for your response.

We are trying to find the differences in load modules(except compile date and time) generated by TEAMA and TEAMB. Even a difference like the above I mentioned should be reported.

I changed X(3) to X(9) and found the BLW for the next 01 level changed and the differences are reported, however if I change to X(6), the BLW for the next 01 level doesn't change and the differences are not reported.

sanaanil · New User Joined: 14 Apr 2005 Posts: 5 Location: Bangalore

Hi Bill,

Although the BLW for both of the programs are different when compiled with Enterprise COBOL 4.1 compiler, the load module differences are not reported.

The same source when compiled with IBM COBOL for MVS & VM 1.2.2 reports the differences.

Bill Woodger · Posted: Wed May 16, 2012 1:02 pm

One Team in Thailand, one Team in India?

I haven't checked what options you are using for the compare.

If you compare the code, you will pick up differences in lengths of Working-Storage items.

You may not get differences if you change the type of the definition. You may, probably more often than not, but you won't be able to rely on it.

If you change working-storage in such a way that a double-word bounday is not crossed, then you may not see any difference "apparent" in the loadmodule. You are more likely to see the difference if you have a VALUE clause on the data.

Again, what are you trying to achieve? I know you are trying to compare things. What are you trying to achieve by comparing?

You have to do source comparison as part of this.

You first need to know exactly what you want to find out from looking at the loadmodules.

Then you need to find out which of those is possible.

Then you need to do it.

Then you need to "fill in" with other solutions for what it is that can't be readily achieved.

Or you need to hire someone for a short time who can set everything up for you from your stated requirements.... :-)

Nic Clouston · Posted: Wed May 16, 2012 1:17 pm

Sawatdee Khrap! Where did the "Thailand" come in? I want that job! Save paying airfares all the time to go and visit all my friends out there!

dbzTHEdinosauer · Posted: Wed May 16, 2012 1:20 pm

overlooked here is that the TS probably does not have the source.

also, you can never prove (other than by compiling/link-editing)
that a source belongs to this load. there are no time stamps.

at least with load modues, you have timestamps.

you can prove the differeneces in load modules,
by comparing their c-sects, which are available via AMBLIST.

if the attributes of a working storage (or linkage) variable are changed,
and it is referenced,
the code generated will be different.

isolation/description of differences, are a second step.
i believe the TS only wants
to prove or disprove that the two load modules are essentially the same,
though possibly compiled/link-edited at different times.

I do believe that comparing load modules of the same source
though generated by different compilers,
will always generate differences if the difference between the two compilers,
is exploited by the difference in generated code by the two compilers.

in otherwords,
if you are trying to compare two load modules of different COBOL Version,
you are wasting your time.

As Bill said, go to the source.
then see what the documented differences are between the two compilers.

sanaanil · New User Joined: 14 Apr 2005 Posts: 5 Location: Bangalore

Hi Bill,

We are doing a project named Automate build, where in the final step is the compare the load modules generated by TEAMA and TEAMB.

During our investigation last week, we have found few weird things happening, one among them is as below.

1. When ABC PIC X(3) changed to ABC PIC X(4), the tools shows up the load module differences, however if the same is put in a copybook the tool doesn't show up the differences.

As you said putting VALUE clause shall help, yes it is. But we cannot change 100s and 1000s of production copybooks. I hope you understand the constraints.

If there is no other way of getting the exact differences between two load modules, finally we will switch to source code comparison.

Thanks a ton to you for quick response......

dick scherrer · Posted: Sat May 19, 2012 8:01 pm

Hello,

Bill Woodger · Posted: Sun May 20, 2012 1:19 am

As you've seen, and has been suggested, comparing the loads might be something that is not going to give you what you want.

If you compare working-storage areas, you can sometimes say for definite that some something is different, but in the case of uninitialised data you may be out of luck.

With no value clause, a PIC X, XX, XXX, XXXX, X(5), X(6), X(7) and X(8) could all "look" the same in a loadmodule, or could look different, depending. So not much use to you. And this can be extended to all data, in groups of eight bytes.

You can have different data definitions, and end up with identical working-storage in a loadmodule.

You have to go to sources. And, if you have them, the best way, to my mind, is the compile listing, as everything that is part of the program is in the listing, any SQL, CICS, COPYBOOKs etc. Let the compiler do the work.