How to fix the colorbar in bar3

Dear all, I would like to plot a bar3 graph. In order to plot bars as functions of their height, I have found the following code:

shading interp
% For each barseries, map its CData to its ZData

for j = 1:length(h)
    zdata = get(h(j),'ZData');
    set(h(j),'CData',zdata)
    % Add back edge color removed by interpolating shading
    set(h,'EdgeColor','k') 
    end
colorbar

My problem is that, during my dynamics, the colorbar changes in time. How can I fix it?

Thanks a lot.