I'm using a DB2 9.7 on AIX and want to change the REOPT parameter for all connecting clients to "REOPT ONCE" (from the default "REOPT NONE"). As far as I read the documentation, I can only set that on client side (either by setting the value or by setting the default package name to NULLIDR1). Is there any more elegant possibility? I also thought about perhaps optimization profiles but that seems to be bound to specific statements and not all...

Here is a useful link for you:
Improve DB2 for Linux, UNIX, and Windows query performance using the REOPT bind option.