WCC authorization token expiration rules?

Hi,

I have made a WCC custom service which executes several core service calls inside. When UPDATE_DOCINFO comes into its turn, an error csInvalidAuthorizationToken occurs. The custom service takes care of that idcToken value is carried over all service calls (added into every request and stored after each to be used at next time).

I have run different test cases so that number of service calls before UPDATE_DOCINFO varies, but at least so far the error occurs every time just at that call.

Is there somewhere documentation over expiration of this authorization token? Or, is there some way to refresh it or get a valid value for it?