If all dimensions of the matrices are greater than MINDIM, another bisection is performed. If any dimension is less than or equal to MINDIM, Strassen's algorithm is terminated and traditional matrix multiplies are performed.
FMS has set the default value of MINDIM based on tests performed on a machine of your type. However, you may want to try some experiments with other values.
Note that FMS makes every attempt to perform low level matrix operations with optimized compute blocks, whose size is NEQBLK. Therefore you will probably obtain the best results by picking values of MINDIM that are an integer multiple of the compute block dimension, NEQBLK.