If you specify:

MINSIZE (600)

GFTAVMA will include only large data sets that are candidates to go directly to tape with hardware compaction. You set 600MB as the minimum size because that is the approximate capacity of a cartridge using IDRC compaction or half the capacity of a 3490E Enhanced Capacity Cartridge System Tape. With 3590, you will want to specify a larger value.

If you specify:

MAXSIZE (600)

GFTAVMA will include data sets that are smaller than 600MB. You can use 600MB as the estimated maximum size to analyze only the data sets that you would consider candidates to intercept and manage with DFSMS.