what is the best place to set autolayout bounds when trying to emulate the grid's AUTO

code currently looks like this but I'm not sure where the proper place to put it is so that I don't get layout cycles or something. It emulate's an Auto, *, Auto row grid.

        var parentHeight = ParentView.Height;

        var headerHeight = Math.Ceiling(_headerLayout.GetSizeRequest(double.PositiveInfinity, double.PositiveInfinity).Request.Height);
        AbsoluteLayout.SetLayoutFlags(_headerLayout, AbsoluteLayoutFlags.WidthProportional);
        AbsoluteLayout.SetLayoutBounds(_headerLayout, new Rectangle(0, 0, 1, headerHeight));

        var footerHeight = Math.Ceiling(_messageSenderView.GetSizeRequest(double.PositiveInfinity, double.PositiveInfinity).Request.Height);
        AbsoluteLayout.SetLayoutFlags(_messageSenderView, AbsoluteLayoutFlags.WidthProportional);
        AbsoluteLayout.SetLayoutBounds(_messageSenderView, new Rectangle(0, parentHeight - footerHeight, 1, footerHeight));

        AbsoluteLayout.SetLayoutFlags(_headerLayout, AbsoluteLayoutFlags.WidthProportional);
        AbsoluteLayout.SetLayoutBounds(_headerLayout, new Rectangle(0, headerHeight, 1, parentHeight - headerHeight - footerHeight));