RE: Dynamic Arrays

[Buck Calabro <Buck.Calabro@xxxxxxxxxxxx>]

>My question to everyone against dynamically
>allocating memory is how much processing time
>and disk space are you loosing if you specify
>an array to be DIM(9999) when you only need 5
>elements but next year you may need 100 and
>the next maybe 1000.  Now weigh that against
>dynamically allocating the array.

I gave up trying to out-think the paging algorithm many years ago.  OS/400
is not MSDOS with an accent.  If you allocate a 16 megs of memory and only
use 1 byte of it, the other 15 and change megs will get paged over.  That
is, the system will KNOW that this memory is unused and will use it
elsewhere.

This does NOT address time to initialise 16 megs of memory, just the working
set size (after the program has been running a while.)

I would say that there needs to be some pretty good justification as to why
dynamic memory is needed rather than use more customary mechanisms like SQL,
OPNQRYF, Logical files or even Load/Sort/Print.  RPG and OS/400 are tailored
to these sorts of workloads and can tune and adapt very well to them.  If
dynamic memory is a better fit, I strongly recommend the iSeries-toolkit
http://www.iseries-toolkit.org/.  Use the wrappers provided there rather
than roll your own.
  --buck