The TIMEL (Time Left) routine from the CERN Program Library keeps track of how much CPU time is left for a job, starting from a default number of seconds (9999).
GEANT by default will properly close down a job when there is no time left. Therefore, users whishing to run for a time longer than the GEANT default must set the start time to a higher value:
This would allow a 10 CPU-hours job in native CPU units.