Dumpcycle
The dumpcycle tells Amanda when to do a full dump in conjunction with the runspercycle parameter. The dumpcycle represents the number of days over which every filesystem will have a full backup. If I want a complete backup of every system every night then my dumpcycle would be 0. Every 7 days would get me a full backup each week.
Runspercycle indicates how many time in the above dumpcycle that the amdump program will be executed. If you do a backup every weekday night but wanted a full backup each week then your dumpcycle would be 7 and and your runspercycle would be 5.