I'd like to write to the stencil buffer without incurring the cost of my expensive shaders. As I understand it, I write to the stencil buffer as a 'side effect' of rendering something. In this first pass where I write to the stencil buffer, I don't want to write anything to the color or depth buffer, and I definitely don't want to run through my lighting equations in my shaders.

Do I need to create no-op shaders for this (and can I just discard fragments), or is there a better way to do this?

As the title says, I'm using OpenGL ES 2.0.

I haven't used the stencil buffer before, so if I seem to be misunderstanding something, feel free to be verbose.