Tomcat shutdown automatically

Question

We are converting files from EPS to EPS using java. If we convert 50 to 100 files, its working fine. If we convert more than 500 files also, it is working fine. But very few times when we convert more than 500 files, Tomcat is shutting down. If we restart the server and give request to convert more than 500 files again, it is working fine. Can someone let me know why Tomcat is getting shutdown automatically in this scenario and what needs to be done?