Passing arguments between fmincon iterations

I have an expensive function

function y = g(x)
x_help=x;
z_x = compute_help_variable(x, x_help);  
y = h(z_x)
end

z_x is a vector, h(z_x) is a scalar.

fmincon will compute g(x0) in a first step and g(x1) in a second step. However, computation of g(x1) would be much faster if I could compute z_x1 = compute_help_variable(x1, z_x0). This means, in the second call of the objective function, I would like to use an intermediate result of the first call. Is there any way to realize this?