depth stencil working now! the flickering is caused by float/GLfloat difference in the rotate function:

before:
 glm::rotate(
            model,
            (GLfloat)clock() / (GLfloat)CLOCKS_PER_SEC / 50.0f
after:
            (float)clock() / (float)CLOCKS_PER_SEC * 80.0f,
Now it works perfect! The GLfloat is not float!!!