Blocking for frameless shower doors

I am redoing a shower and will have frameless shower doors installed. I know I need blocking for where the glass attaches to the wall, but I am not sure the best way to do it. I have seen some say to put two 2x4 studs together vertically in the wall centered on the curb. Some say use 3 2x4's. Others say to turn the 2x4 so the wide side faces the wall so there is no chance of a screw going between the 2x4's. Some have even said to use a 2x6 to allow more room for "error". Anyone have any suggestions? Thanks.

 

This is how mine was done by a contractor. 2x4" laid flat but do it anyway you want. At least use 2x4's and no 2x3's unless it's tight for space. The home was built with a mix of studs. Wood if it was a supporting wall, metal for everything else.

 

Can't beat 2 x 6 vertical and flat. Definitely best practice.