I think you need to read something rather than blindly dumping things into Matlab. You need to have an understanding of poles and zeroes.
For your system, you've got a pole at -j2 and 0. zeta (damping) has values of 1 and -1 because the poles lie on the j-axis (zeta is a function of the angle of the pole from the j-axis)
Sorry, you're right about the pole at -2. Damping is related to the angle from the REAL axis, zeta=cos(angle). Since you angle is 0 (and 180), cos(0)=1,-1