How to find the static stall angle of attack for a given airfoil at given Re?
Being a symmetric airfoil, the NACA 0012 does not have a particularly high maximum lift coefficient, especially at low Reynolds numbers. And yes, 300,000 is considered a low value for the Reynolds number of airfoils. On the other hand, there is no other airfoil that has been tested so much. You will find data all over the place.

Generally, the angle of attack range of interest for aeronautics is where little to no separation of the flow along the surface occurs. This is restricted to a small range around 0° (when the flow is hitting the airfoil more or less head on). Larger separation reduces lift, so right before separation first lets lift drop a little, the stall angle of attack has been reached.


180° polar for several airfoils

But stall is not the end of lift. See above for 2D wind tunnel data collected by S. Hörner in his book Fluid Dynamic Lift. These results have been collected at a higher Reynolds number when the stall angle of attack is shifted to higher values. To be honest, a lot of factors influence this. In your case, even though there is another maximum at about 45°, the stall angle of attack is between 9° and 10°. Not more.