I need help with this lagrange problem

We are given a function f(x,y,z)=z^2-2z+xy and we restrict (x,y,z) to lie in the solid cylinder D:x^2+y^2<(or equal) to 2 (and z arbitrary).At what point(s) of D does f attain its minimum value?

Well the problem is with the z arbitrary..do they mean that the constraint is x^2+y^2+z^2<2?

thank you