This determines whether 1 or 2 partitions will be created. By default LICKS does not give you a choice here. If the card is 2GB or less a single partition will be created. If it is larger than 4GB then two partitions will be created - a small 16MB one containing DISKBOOT.BIN and the other will hold the SDM folders (SCRIPTS etc), photos and movies. 4GB cards can be formatted as one or two partitions.
Ypou can change this behaviour by editing the licks.properties file and increasing the value of 'max1size' or decreasing the value of 'min2size'.