Tomcat – java.lang.OutOfMemoryError: PermGen space

Tomcat – java.lang.OutOfMemoryError: PermGen space
When you have access the .jsp page then some time it shows the following error on the page.
============================
HTTP Status 500 –
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Servlet execution threw an exception
root cause
java.lang.OutOfMemoryError: PermGen space
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.25 logs.
Apache Tomcat/5.5.25
============================
We need to increase the memory by make change in catalina.sh or catalina.bat file.
Use the  following steps :
1) vi /usr/local/jakarta/tomcat/bin/catalina.sh
2)  Add following line into the catalina.sh file.
JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms512m -Xmx1024m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+DisableExplicitGC"
Partial example of catalina.sh file
=============================================
#   JSSE_HOME       (Optional) May point at your Java Secure Sockets Extension
#                   (JSSE) installation, whose JAR files will be added to the
#                   system class path used to start Tomcat.
#
#   CATALINA_PID    (Optional) Path of the file which should contains the pid
#                   of catalina startup java process, when start (fork) is used
#
# $Id: catalina.sh 609438 2008-01-06 22:14:28Z markt $
# —————————————————————————–
JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms512m -Xmx2048m -XX:NewSize=512m -XX:MaxNewSize=512m -XX:PermSize=512m -XX:MaxPermSize=512m -XX:+DisableExplicitGC
# OS specific support.  $var _must_ be set to either true or false.
cygwin=false
os400=false
darwin=false
=====================