Re: question on BLK vs. NOBLK compiler option...

On Tue, 28 Nov 2006 11:22:25 -0500, Michael Rosinger wrote

List,

Another question related to the migration of our COBOL programs from 
VSE to iSeries. We have a lot of sequential files that have a BLOCK 
CONTAINS clause specified in the FD. I see that the default compiler 
option is NOBLK and I am getting a "LNC0662 For file %1, BLOCK 
CONTAINS clause syntax checked only." informational message in my compiles.

So what it is best to use (BLK or NOBLK) and why? TIA

The parameter you reference has nothing to do with the Block Contains clause -
which is ignored on the System i (I think it is on VSE as well but ...)

It has to do with whether you want to overrule the compiler's defaults for
blocking.

The compiler will automatically block and file that is processed sequentially
- but will not block any file for which a read by key operation exists.  If
you _know_ that you are reading by key only to position prior to a read next
sequence then using the BLK to force blocking will help performance.  You can
also control blocking via the OVRDBF but that is a separate blocking operation
(i.e. how much of the file is retrieved into the OS buffers whereas BLK
controls the program's buffers).

Would write more but I'm on dial up today and can't research the stuff.


Jon Paris