Bind LayoutBounds of AbsoluteLayout

I've downloaded a XAML sample of a demo that Xamarin provided of a ListView displaying a determined class (NamedColor). I've adapted that code and now I would like to have my label (which is inside the AbsoluteLayout) using a binding. I am currently using AbsoluteLayout.LayoutBounds="0,10,50,50" which fits my android but I would really like to have something like AbsoluteLayout.LayoutBounds="0,(rowHeight-boxSize)/2, boxSize ,boxSize". I previously tried not using the absoluteLayout and added the following properties xAlign="Center", yAlign="Center", WidthRequest="{StaticResource boxSize}", HeightRequest="{StaticResource boxSize}" but in some Cells the label couldn't stay with the height requested, so I decided to use the AbsoluteLayout.

My code:

(...)
<ContentPage.Resources>

  <!-- This is only an issue on the iPhone; Android and 
       WinPhone auto size the row height to the contents. -->
  <OnPlatform x:Key="rowHeight"
              x:TypeArguments="x:Int32"
              iOS="80"
              Android="80"
              WinPhone="105" />

</ResourceDictionary>

</ContentPage.Resources>

<ListView.ItemTemplate>


<ViewCell.View>

           <AbsoluteLayout>
             <Label Text="{Binding Class}"
             AbsoluteLayout.LayoutBounds="0,10,50,50" 
             Font="Bold, Large" TextColor="Black
             BackgroundColor="{Binding Color}"

           </AbsoluteLayout>

           <StackLayout Padding="5, 0, 0, 0" VerticalOptions="Center">
             <Label Text="{Binding Name}" Font="Bold, Medium" />

             <StackLayout Orientation="Horizontal" Spacing="0">
              <Label Text="{Binding dateTime}"/>
            </StackLayout>

           </StackLayout>
        </StackLayout>
      </ViewCell.View>
    </ViewCell>
  </DataTemplate>
</ListView.ItemTemplate>

(...)

Previous label code:

          <Label Text="{Binding Class}"
                   Font="Bold, Large" TextColor="Black"
                   BackgroundColor="{Binding Color}"
                   WidthRequest="{StaticResource boxSize}"
                   HeightRequest="{StaticResource boxSize}"
                   XAlign="Center" 
                   YAlign="Center"/>

There is a image file attached with the ouput of the AbsoluteLayout vs WitdthRequest&HeightRequest.

Thanks in advance