Altering output file attributes

f8ful · New User Joined: 02 Nov 2006 Posts: 30

I have a sequential file I'm modding to. When I run a batch job to mod the file the attributes of the "modded to" file are being changed. How can I prevent this?

Before attributes of the input and output file:

Record format . . . : VB
Record length . . . : 0
Block size . . . . : 32760

Attributes after modding:

Record format . . . : VB
Record length . . . : 32756
Block size . . . . : 32760

The JCL I've tried to mod

//STEP2 EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1 DD DSN=(Indataset),DISP=SHR
//SYSUT2 DD DSN=(Outdataset),DISP=MOD,
// DCB=(RECFM=VB,LRECL=0,BLKSIZE=32760)
//SYSIN DD DUMMY

and

//SYSUT1 DD DSN=(Indataset),DISP=SHR
//SYSUT2 DD DSN=(Outdataset),DISP=MOD,
// DCB=(RECFM=VB,BLKSIZE=32760)

and

//SYSUT1 DD DSN=(Indataset),DISP=SHR
//SYSUT2 DD DSN=(Outdataset),DISP=MOD

All JCL has produced the same results.

There must be some type of JCL coding that will prevent the LRECL from changing.

Thanks.

Robert Sample · Posted: Tue Oct 06, 2020 6:39 pm

sergeyken · Posted: Tue Oct 06, 2020 7:30 pm

Parameter LRECL (and other DCB subparameters) from DD statement always have priority over the same values stored in DSCB (e.g. “dataset control block”). Whenever your output dataset is OPEN/CLOSED, those high-priority values do mandatory replace the previous ones.

BTW: if no LRECL>0 were defined anywhere, then most likely you would get OPEN ABEND...

steve-myers · Posted: Tue Oct 06, 2020 7:57 pm

The probability is high that it was IEBGENER that changed the LRECL, because it was 0. Look in the IEBGENER SYSPRINT data set: I think you will see a message that it copied the input LRECL to the output LRECL.

Mr. Sample is incorrect when he says LRECL 0 is valid only for RECFM U. It is always valid when allocating a data set; it must be set before opening the data set for the first time. For V record formats the LRECL defines the maximum length for the data set. The exception to that particular rule is RECFM U data sets where BLKSIZE defines the maximum record length; Assembler programs that use QSAM to write to the data set use LRECL to specify the length of the next record the program is writing to the data set.

f8ful · New User Joined: 02 Nov 2006 Posts: 30

Thanks all. In particular Steve Myers. Yes it was IEBGENER with the SYSPRINT message you mentioned, causing the problem. I used another utility to do the MOD and it did not change the LRECL upon the mod.

sergeyken · Posted: Wed Oct 07, 2020 5:28 pm