In WebLogic Console, check your Maximum Capacity for the EBSDataSource Data Source, and increase it to 1000 or 2000. Also make sure your database sessions and processes will support more than 3000 sessions.
OACORE crashes happened for several customers if not properly tuned and right patches are applied. Let me know EBS version so that I can suggest few things.
Also check the below:
- Apply latest OACORE patches from Doc ID 2087130.1
- Increase StuckThread time out
- Increase the Heap Memory, PermSize settings for the oacores