Is there an easy way to set all memory settings to default? I am not sure where to check this or how to do it.

I have a server on NW65sp5 with the nw65os5a patch... Could this be an issue with Apache or the new server.exe? or the memory settings. The server will state that it is out of allocated memory and then hang "frozen"...no abend, no nothing...it just won't do anything. I have to hard boot it to get it back up. Then it runs for a while...maybe a few days...then repeats...