[mod_python] textarea form size problem

Hello!
i'm having problems with the size of textarea. i have to copy a xml
file  to the textarea, but i can't get the entire value using cgi
module. Why?

<TEXTAREA name="sign_swml" rows=10 wrap="off" cols=42></TEXTAREA>

import cgi
form =cgi.FieldStorage()
a = form.getvalue('sign_swml')

there are a limit size to get the value of textarea?

Juliano Freitas