How much geometry can you render in memoryless render pass?

I've got an iOS application that renders a lot of geometry. (Lots of objects and in most cases multiple instances of those objects) The app was previously running using OpenGL ES 3.0. I'm just starting in my conversion but already I'm getting the following error:

Execution of the command buffer was aborted due to an error during execution. Too much geometry to support memoryless render pass attachments. (IOAF code 13)

Is there any way to have some idea of how much geometry is too much? If I continue to get this error, does that mean that I need to switch from a memoryless render pass to two render passes, the first one writing to system memory and the second reading from system memory to perform the lighting?

Thanks for any insight anyone can give.