Zend Framework comes with a standard set of config classes which are ready for you to use. Config handles setting various configuration such as where a cookie lives, lifetime, including several bits to configure ext/session when using Zend\Session\Config\SessionConfig.
In the event that you prefer to create your own session configuration; you must implement Zend\Session\Config\ConfigInterface which contains the basic interface for items needed when implementing a session. This includes cookie configuration, lifetime, session name, save path and an interface for getting and setting options.