FFT Speed up Generation

Hey there

I d like to use the MKL library to generate the 1D FFT(complex to complex), with the size of 256.

To speed up the process i want to split the 256 FFT vector to 4 sub-vectors of 64 and run each on 1 thread (i have 4 threads on my processor).

How with the help of OMP library i can get all the sub-vectors executed simultaneously in the parallel mode? Any help or programming details will be apperciated.

Thanks