By default the sizes are minimum 100MB and Maximum 200MB, to increase

1. Edit the following file and add the below lines

vi  /var/cpanel/tomcat.options

Note: If the file does not exists, create it.

2. Add the below lines in the files which defines the minimum and maximum heap sizes (change the values to your desired values)

-Xmx800M
-Xms500M

save the file and exit.

3. Restart the tomcat service using the below command.

/etc/init.d/easy-tomcat7 restart