Post too Large Issue

I'm using Apache 2.4 with Glassfish 2.1 and I keep getting this error with large posts:

java.lang.IllegalStateException: Post too large

I've already tried to change the property maxPostSize of the Glassfish http-listener to a lot of values (and even 0, to accept everything) but nothing seems to work.

Do you guys know of any other thing that might be an issue here?

PS: The post has only 4MB. I think that anything bigger than 2Mb is being rejected.