Movemesh23 for meshS

Hi all,

I am trying to simulate crack propagation in Thin Layer using FreeFEM++.
I use the command movemesh23

mesh th = square(n, n, [-1*L0+(L0+L0)*x, -1*h0+(h0+h0)*y],flags=1);
meshS Th=movemesh23(th,transfo=[x,y,z]);
plot(Th);

The result is well, but can the layer thickness be specified in this code?
How thick is the layer?