how to see how many files an app is trying to open?

Greetings, admins. We have an app (java) running on T64 v5.1A that wants
to open huge numbers of files, and we are trying to tune the system to
allow it to open those files, but no one really knows just *how* many
open files it will max out at. 

I'm told this is one thread, opening all these files. We raised
open_max_soft and open_max_hard, but the app still crashes at 4092 open
files, and it's unclear to me what limit it might be hitting.

I can't figure out a good way to even look at this. "lsof" will work,
but it's clumsy - seems like there should be a "ps" option, but I am not
finding it - or some other way.

Suggestions? TIA! 

Judith Reed