framework/web/Session.php
public function setUseCookies($value)
    {
        $this->freeze();
        if ($value === false) {
            ini_set('session.use_cookies', '0');
            ini_set('session.use_only_cookies', '0');
        } elseif ($value === true) {
            ini_set('session.use_cookies', '1');
            ini_set('session.use_only_cookies', '1');
        } else {
            ini_set('session.use_cookies', '1');
            ini_set('session.use_only_cookies', '0');
        }
        $this->unfreeze();
    }
public function setUseCookies($value)
    {
        $this->freeze();
        if ($value === false) {
            ini_set('session.use_cookies', '0');
            ini_set('session.use_only_cookies', '0');
        } elseif ($value === true) {
            ini_set('session.use_cookies', '1');
            ini_set('session.use_only_cookies', '1');
        } else {
            ini_set('session.use_cookies', '1');
            ini_set('session.use_only_cookies', '0');
        }
        $this->unfreeze();
    }
Sets the value indicating whether cookies should be used to store session IDs.

Three states are possible:

- true: cookies and only cookies will be used to store session IDs.
- false: cookies will not be used to store session IDs.
- null: if possible, cookies will be used to store session IDs; if not, other mechanisms will be used (e.g. GET parameter)

@param bool|null $value the value indicating whether cookies should be used to store session IDs.