php-persistent-sessions.php

<?php

// Persistent sessions.
session_name('your-name');

// Because your sessions in common folder could get collected by gc
// started by another script where this sessions aren't set.
ini_set("session.save_path", dirname(__FILE__) . '/tmp/');

// Decreases chance that gc process is started
// on every session initialization from 1% to 0.1%
ini_set("session.gc_divisor", 1000);

// Keep cookies and session files as long as possible.
ini_set("session.gc_maxlifetime", 2592000);
session_set_cookie_params(2592000);
session_cache_expire(2592000);