Like most of you, I also encountered the problem that you're logged out from your websession after 60 minutes of inactivity (Default value).
But now you have in version r11.2 the following item in the online help:
To prevent sessions from expiring due to activity, set this Option's value to 0. Sessions may still be invalidated by other methods, such as logoff routines.
When doing so, keep an eye on the performance of the web server.