Maybe i qas not exact enough.
With 1GB of RAM i could add a layer, but my machine was paging.
I have added one more, so i have now 2GB of RAM, and i get this message when i try to add a new layer.
So with 1 GB i could have base + 1 layer.
With 2 GB i could not add an additional layer.
My question is how much RAM would a noew layer consume?
I know that my image is large, but i could not reduce the size.