Thank you all!
The top of 2x12s is flush with the top of glulam for its full length. The column (colium or columb per some other post) cap at the cantilever is 14" high and there is no additional column bracing. I suppose that some kind of lateral restraint is provided by the column/cap against the buckling of the the bottom/compression face of the glulam at the column, but I would think it to be minimal, almost impossible to calculate, and even if I concocted some kind of calculation I probably wouldn't feel comfortable with it. I think it is a hinge. I am specifying an added brace for the top of the column.
Regarding the contribution of the 2x12s at 16" o.c. to the restraint against buckling of the bottom face of the glulam where it is in compression, whereas a full depth 28.5" deep joist at 16" o.c. would plainly provide adequate bracing, and a 3.5" deep joist would plainly not provide adequate bracing, and there must be some intermediate depth somewhat less than 28.5" that we might consider as providing adequate bracing, I do not think 11.25" is that depth, and quite likely not even close to that depth. How's that for a running on sentence!! I'm going to specify additional compression (bottom) face bracing. But I would like to know how to determine that "intermediate depth" that would provide bracing.
Thanks!