If you are running SOLR or any other high memory process, there is a chance, you have seen the OutOfMemory exception. You can increase the heap-size using WAS or directly in the file. Recommended approach would be directly in the file.
From WAS console:
Directly updating the file, as this is the same file that gets updated while changing WAS console: On toolkit, this would be the path
C:\WCDE_ENT70\wasprofile\config\cells\localhost\nodes\localhost\servers\server1\server.xml
Search for initialHeapSize and maximumHeapSize and change
initialHeapSize=512
maximumHeapSize=1536
or you have only 1024 try
initialHeapSize=1024
maximumHeapSize=1024
If you give incorrect values here, it could result in your server not starting so please be cognizant about that.