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Sysaron · Posted: Sun Feb 22, 2004 6:42 pm Post subject: Adding to a file if the DISP=OLD?

Could you add more data sequencially if the file disp=OLD, of does it have to be disp=MOD? Will the previous data be overwritten if file is disp=old?

slade · Posted: Sun Feb 22, 2004 10:43 pm Post subject:

Hi,

To add data recs to a PS file use MOD. If you use OLD and write to the file, the existing data will be overwritten. Also, the data not overwritten is no longer available unless extraordinary methods are used to recover it.

HTH, Jack.

Cogito-Ergo-Sum · Posted: Mon Feb 23, 2004 2:56 pm Post subject:

Err, Jack...

Don't you mean,

Maton_Man · Beginner Joined: 30 Jan 2004 Posts: 123 Topics: 0

Not true Cogito-Ergo-Sum.

One example - If the dataset you were writing to was a member of a PDS then it would be rewritten at the end of the PDS and the previous space taken up by the member would be marked as inaccessible until a compress was done. This data could be accessed by means of stealth!
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superk · Advanced Joined: 19 Dec 2002 Posts: 684 Topics: 5

From the COBOL manual:

To add to a QSAM file, open the file as EXTEND and use the WRITE statement to add records immediately after the last record in the file.

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IGY3PG10/1.9.2.3?DT=20020923143836#HDRWQ303

Maton_Man · Beginner Joined: 30 Jan 2004 Posts: 123 Topics: 0

You've lost me Superk?! When did COBOL come into the equation?
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My opinions are exactly that.

superk · Advanced Joined: 19 Dec 2002 Posts: 684 Topics: 5

Since JCL cannot by itself accomplish anything with data, other than to allocate the appropriate dataset using the specified disposition, then some sort of program must be invoked to accomplish the creation and/or addition of data to the dataset. Since no reference was made to any particular program requirements, I presume that any type of program is open for discussion within the context of this subject.

semigeezer · Posted: Tue Feb 24, 2004 12:45 am Post subject:

slade · Posted: Tue Apr 20, 2004 10:01 am Post subject:

Superk is correct. Using the appropriate OPEN in most languages will allow extension of a PS file. But you usually don't have that capability when using utilities. You're stuck w/OLD or MOD, so be careful, you can overwrite the existing data.

And CES, I did mean "not overwritten". You could probably use DITTO or some other sysprog magic, provided the data beyond the file mark was not reallocated and overwritten by another task.

Regards, Jack.