  We analyse transverse oscillations of a coronal loop excited by continuous
monoperiodic motions of the loop footpoint at different frequencies in the
presence of gravity. Using the MPI-AMRVAC code, we perform three-dimensional
numerical magnetohydrodynamic simulations, considering the loop as a magnetic
flux tube filled in with denser, hotter, and gravitationally stratified plasma.
We show the resonant response of the loop to its external excitation and
analyse the development of the Kelvin-Helmholtz instability at different
heights. We also study the spatial distribution of plasma heating due to
transverse oscillations along the loop. The positions of the maximum heating
are in total agreement with those for the intensity of the Kelvin-Helmholtz
instability, and correspond to the standing wave anti-nodes in the resonant
cases. The initial temperature configuration and plasma mixing effect appear to
play a significant role in plasma heating by transverse footpoint motions. In
particular, the development of the Kelvin-Helmholtz instability in a hotter
loop results in the enhancement of the mean plasma temperature in the domain.
