  We applied a relativistic configuration-interaction (CI) framework to the
stabilization method as an approach for obtaining the autoionization resonance
structure of heliumlike ions. In this method, the ion is confined within an
impenetrable spherical cavity, the size of which determines the radial space
available for electron wavefunctions and electron-electron interactions. By
varying the size of the cavity, one can obtain the autoionization resonance
position and width. The applicability of this method is tested on the
resonances of He atom while comparing with benchmark data available in the
literature. The present method is further applied to the determination of the
resonance structure of heliumlike uranium ion, where a relativistic framework
is mandatory. In the strong-confinement region, the present method can be
useful to simulate the properties of an atom or ion under extreme pressure. An
exemplary application of the present method to determine the structure of ions
embedded in a dense plasma environment is briefly discussed.
