ICAO do not issue licences - they are part of the United Nations. Member states (of ICAO) issue licences using the guidelines provided by the Standards and Recommended Practices (SARPs) for Flight Crew Licensing contained in Annexes to the Chicago Convention. Even then, member States do not have to follow the SARPs - the only obligation they have is to notify ICAO of any differences.
There really is no such thing as an "ICAO" licence...