Holding procedures
What is the best efficient procedure that ATC can apply to manage holds?
I suppose 2 options:
1. To vector a/c into the hold at any of the altitudes (flight levels) that is vacated in the hold at the moment. To vector a/c out of the hold from any required altitude (flight level), calculated with computer or by person.
2. Aircrafts always occupy flight levels in the hold from bottom to top. A/c is vectored into the hold at first lower unoccupied flight level and is vectored out of hold at the bottom flight level of the hold. While in the hold all a/crafts are instructed to descend to the next lower level from time to time, so all stack is moving from top to bottom.