Please, take a look at the site below. Also you can check function "fdesign.comb" from DSP System Toolbox.
In addition, I would also suggest you to read this paper:
R. Teymourzadeh and M. B. Othman, “An enhancement of decimation process using fast cascaded integrator comb (CIC) filter,” in Proc. IEEE International Conference on Semiconductor Electronics (ICSE’06), 2006, pp. 811–815