Gains optimization procedure based on constraints specified on the root locus

I'm using the control system toolbox provided by matlab to estimate the gains of my controller: using root locus design I get a graph like this one

My question is: what is the x on the x-axis? maybe a pole position at a previous iteration of the optimization procedure that I have run to find a gain value that satisfies my requirements? It shouldn't be the open loop pole position, because my system is formed by two integrators multiplied by a constant (1/inertia). Thanks

I start from the following simulink diagram:

my trasfer function is g_theta = 1/I_y*s^2 (considering continuous time) with Iy = 0.0054 and then I select analysis , control design, compensator design. I select Kp and Kd as the gains to be tuned, and I use the root locus for specifying the constraints. Then I click in SISO Design Task, automated tuning, optimize compensator, which automatically tries to find gain values to satisfy my constraints. The white are is the area that satisfies the constraints, and I think that the pink squares are my poles position after having been completed the optimization procedure. This is correct? But in this case, what is the x(pole) shown? Thanks