A FLASH memory control technique with wear leveling between the different blocks of the FLASH memory. By a controller managing the blocks of a FLASH memory within a data storage device, some of the blocks are pushed into a spare queue waiting to be allocated as data blocks or system blocks and some blocks are pushed into a jail queue to be inaccessible. When the jail queue is full and any block within the spare queue has an erase count greater than any block within the jail queue, for wear leveling between the different blocks within the FLASH memory, the controller releases a first block selected from the jail queue and pushes a second block selected from the spare queue into the jail queue.