Re: Using CL to call RPG pgms

[Tony Carolla <carolla@xxxxxxxxx>]

Hmmm... I think you quoted the wrong section of my reply, because 
Block(*YES) on the F-spec says to use read blocking, not specify a DS that 
the file is read into... 

As far as I know, specifying BLOCK(*YES) on the F-Spec overrides the 
decision criteria the compiler uses to determine whether or not to read 
ahead in the file when an input operation is executed. I don't know the 
exact criteria, but I believe that if you only do READs, and no READEs, 
CHAINs, etc, then blocking is done by default, without the BLOCK keyword. 

I always specify BLOCK(*YES) or BLOCK(*NO), but that's probably a 'control 
freak' issue I have. 

But in addition to doing this, I also specify the overridden block size 
(number of records read), because I sometimes want to read more than the 
default. I believe the default # of records is 4k-worth of records, whereas 
there is a 128k buffer available for all files using blocking. It might be 
more if the job runs in batch, not sure. 

If I build a program that needs to read all, or a large number of records 
from a file, and If I run this program on a system with plenty of memory, 
and it is in a pool that has enough of this memory allocated, then it is 
unlikely that the memory allocated to my program will be 'swapped' to disk 
often, so I take advantage of the full 128k, and tell the system to 'fill-er 
up' each read. This minimizes disk I/O transactions, and runs alot faster. I 
have done extensive benchmarking using this technique, and it works well. 

And that is why I wish that, in addition to saying Block(*YES), you could 
say Block(*YES:xxxx), specifying the number of records to read each input 
operation. 

On 9/2/05, Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx> wrote:
> 
> 
> > Sure! I would love to! As soon as I can specify a DS that the 'primary' 
> file
> > can be READ into by the hidden cycle details. Oh... wait... you can only
> > have one primary file, right? <vbg> hehe... no thanks.
> 
> Couldn't you achieve the same thing by specifying BLOCK(*YES) on your
> F-spec?
> --
> This is the RPG programming on the AS400 / iSeries (RPG400-L) mailing list
> To post a message email: RPG400-L@xxxxxxxxxxxx
> To subscribe, unsubscribe, or change list options,
> visit: http://lists.midrange.com/mailman/listinfo/rpg400-l
> or email: RPG400-L-request@xxxxxxxxxxxx
> Before posting, please take a moment to review the archives
> at http://archive.midrange.com/rpg400-l.
> 
>