Changing the depth/stencil.

gistfile1.cs

// Create a new depth buffer.
var newDepthBuffer = GL.GenRenderbuffer();

// Set the format and size of the new depth buffer.
GL.BindRenderbuffer(RenderbufferTarget.Renderbuffer, newDepthBuffer);
GL.RenderbufferStorage(RenderbufferTarget.Renderbuffer, RenderbufferStorage.Depth24Stencil8, width, height);

// Attach the new depth buffer to the default backbuffer.
GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0);
GL.FramebufferRenderbuffer(FramebufferTarget.Framebuffer, FramebufferAttachment.DepthStencilAttachment, RenderbufferTarget.Renderbuffer, newDepthBuffer);