color on the stencil buffer

I am working on the application by using stencil buffer. I drew the big solid sphere
and used glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP).
I created the small solid sphere by using stencil buffer glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE).
It worked fine.
Then I drew the vector on the stencil buffer and used glStencilOp (GL_ZERO, GL_ZERO, GL_ZERO).
It displayed the color of the sphere and the
black color on the vector.

How can I change the color of the vector
on the stencil buffer?

Thanks.

The stencil buffer does not keep color values so you question is not very easy to understand. You drew a vector? Is that an arrow and the length depending on the size of the vector or do you mean something else?