I'm trying to deploy an app into tomcat..but after uploading the war file..it the tomcat manager always shows permgen error
could anyone help me why is this error occuring..my tomcat server has around 128MB runtime memory and the war file is only around 25MB??
thank you.

i can't see \tomcat folder\bin folder as mentioned in your first link when i access it through ftp

.my tomcat server has around 128MB runtime memory

Is that 128 MiB just for permagen space or total JVM memory? Unless you explicitly specify permagen size, a small number like I guess 64 MiB is picked up (depending on your exact JDK version, OS version/flavour etc.) which is certainly not enough for "enterprise" Java. So to be clear, permagen memory settings are different from the normal Java heap settings.

For Java versions < JDK 7, the permagen space contains the loaded classes, string pools and other metadata. When you start up a web container, it not only loads the JDK classes but also classes from the Tomcat JAR files which is by no means a small number.

Check the command line in Tomcat you are using to spawn/start the server and search around (using Google) ways to configure permagen for Tomcat.

EDIT: Maybe this link