SessionState is a Boolean property that indicates persistent sessions are used by the HTTP server to service requests from peer threads. SessionState is used by CreateSession to determine if a new persistent session is created and added to the session list. 

SessionState is used to get the cookie value for a session, and to determine if a persistent session matching the 'IDHTTPSESSIONID' cookie and Remote IP address should be retrieved from the session list. 

The default value for SessionState is Id_TId_HTTPServer_SessionState, as assigned during initialization of the component.

CreateSession 

GSessionIDCookie