session_start() doesn't reset session.cookie_lifetime?

Let's say session.cookie_lifetime = 30; this of course kills the session 30 seconds after it was created. Is there a way to have every session_start() 'renew' the life of the clients cookie? Meaning the session would expire 30 seconds after the LAST session_start() call. My goal is to have my sessions expire after 5 minutes of inactivity. Also, will PHP clean up the session files on it's own? Thanks, Chris -- "What's the Constitution between friends?" - TIMOTHY J. CAMPBELL - Response to President Cleveland, who refused to support a bill because it was unconstitutional