Good point about using "F11=Display tuning data " on WRKSHRPOOL to set
limits. I often use that to set a minimum but I often leave the maximum
at 100%. To each his own. I can understand a maximum. Do you really
want the interactive query from hell to suck all memory out of all the
other subsystems? OTOH there are other methods to control that query but
it does serve as an example of why a maximum may be desired.
I wouldn't choke it too tight as to where you have a heavy interactive
load going on today and nothing in batch but you still have all this
memory in batch not doing anything.