Each set of resources is allocated only for the period of {HEAD ~ time} needed to perform {TAIL ~ the required function} 
needed to perform
Each set of resources is allocated only for the period of { HEAD ~ time } needed to perform { TAIL ~ the required function }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL