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Gumby
New User
Joined: 05 Jan 2010
Posts: 1
Location: chennai
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I'm new to ASM. I've been trying to learn asm by myself and in one of my practice programs I keep getting s0c4 upon execution. I'm not able to pinpoint what's wrong. Could you please let me know where I'm going wrong?.
| Code: |
ASMPGM6 START 0
SAVE (14,12)
BALR 12,0
USING *,12
PARA1 EQU *
OUTREC DS 0CL80
OPEN (OUTFILE,(OUTPUT))
MVC OUTREC,=C'HI'
PUT OUTFILE,OUTREC
CLOSE (OUTFILE)
RETURN (14,12),RC=0
OUTFILE DCB DSORG=PS, X
RECFM=FBA, X
MACRF=PM, X
BLKSIZE=800, X
LRECL=80, X
DDNAME=OUTP
END
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run job for the above program is as below
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//STEP1 EXEC PGM=ASMPGM7
//SYSPRINT DD SYSOUT=*
//SYSOUT DD SYSOUT=*
//OUTP DD DSN=E4912.OPT,
// DISP=(MOD,CATLG,),
// SPACE=(CYL,(1,1),RLSE),
// LRECL=80,RECFM=FBA,BLKSIZE=800
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Rgds,
KV |
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enrico-sorichetti
Superior Member
Joined: 14 Mar 2007
Posts: 10873
Location: italy
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| Code: |
OUTREC DS 0CL80
OPEN (OUTFILE,(OUTPUT))
MVC OUTREC,=C'HI' |
the quoted code will overlay the program with garbage!
read the pop for the MVC specifications!
it' s always a bad practice to have to working areas interspersed with the executables
also nothe that a DS 0<something> does not reserve any storage,
it sipèly define an address and a length |
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UmeySan
Active Member
Joined: 22 Aug 2006
Posts: 771
Location: Germany
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@ Gumby !
And please, read more about structured programming.
Do not code anything one after the other. Build structures. Use sections.
Code assembler as you would code cobol. |
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Stu Thomas
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Joined: 06 Feb 2010
Posts: 5
Location: Canada
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| OPEN and CLOSE do not need a save area, but PUT does. You need to provide a save area - that will solve your problem. |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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| Stu Thomas wrote: |
| OPEN and CLOSE do not need a save area, but PUT does. You need to provide a save area - that will solve your problem. |
Huh? And THAT said by a system programmer?
I did write enough assembler programs to know that you are
talking nonsense. |
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Stu Thomas
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Joined: 06 Feb 2010
Posts: 5
Location: Canada
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| Please explain your comment about "nonsense". |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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LOL,
well PUT doesnt need a save area.
So what do you think your comments look like. |
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Stu Thomas
New User
Joined: 06 Feb 2010
Posts: 5
Location: Canada
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PUT results in a BALR 14,15 to an Access Method. The first thing that the Access Method does is to store YOUR registers into the save area pointed to by Reg 13. Reg 13 currently points to the save area which was passed to your program by your caller. Therefore, the Access Method is writing into your caller's save area. Thus, the Access Method has overlaid your caller's save area. When you return to your caller at the end of your code, you have not restored your caller's registers - you've got the registers which were saved by the Access Method. The 0C4 results. This is a common problem, often seen when people do not understand when save areas are required. It is also common to see people providing save areas when they are not necessary, but this will not cause abends, just unnecessary instructions, and wasted time.
Do you need any further explanation? |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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Of course not but what you commented looked like supplying a save area for any PUT.
But supplying a save area at the start of your programming is a required practice. I even think that the OPEN/CLOSE will use it.
So im sorry for mis interpreting your comment.
Hope there is no harm done. |
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Stu Thomas
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Joined: 06 Feb 2010
Posts: 5
Location: Canada
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| Sorry, but that is not correct. OPEN and CLOSE use the save area in the RB; they do not require that you provide a save area in your program. And, as I explained, "supplying a save area" is NOT a required practice. |
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Stu Thomas
New User
Joined: 06 Feb 2010
Posts: 5
Location: Canada
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One more thing as I re-read your answer. Even though I did not state this, ALL PUTs need a save area.
Also, I accidently missed your apology. There's never any harm done since we are all trying to help each other. I'm not offended. And yes, I actually am a System Programmer, and I've been one since 1967, in the days of PCP. MFT and MVT. I learned assembler from the original Principles of Operation, and I know what a challenge understanding it can be. I'm glad to provide any assistance if it will help folks who are new to assembler to solve their difficulties. |
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