  Extended de Gennes-Fisher (EdGF) local-functional method has been applied to
the thermodynamic Casimir effect {\it away} from the critical point for systems
in the Ising universality class confined between parallel plane plates with
symmetric boundary conditions (denoted $(ab)=(++)$). Results on the universal
scaling functions of the Casimir force $W_{++}(y)$ ($y$ is a
temperature-dependant scaling variable) and Gibbs adsorption $\tilde G(y)$ are
presented in spatial dimension $d=3$. Also, the mean-field form of the
universal scaling function of the Gibbs adsorption $\tilde G(y)$ is derived
within the local functional theory. Asymptotic behavior of $W_{++}(y)$ for very
large values of the scaling variable $y$ is analyzed in {\it general} dimension
$d$.
