Photolysis of the HCl molecule surface solvated on clusters with 2 to 12 argon atoms is investigated by means of quantum molecular dynamics simulations. Two basic questions are addressed: (i) How does the cage effect change upon increasing the size of the cluster, and (ii) how can caging be influenced by an infrared (IR) excitation of HCl hindered rotation (libration) prior to ultraviolet (UV) photolysis. The efficiency of caging is discussed in terms of measurable quantities. In the time domain, temporary populations of the trapped hydrogen atom are monitored, while in the energy domain short-lived vibrational resonances are observed as a fine structure in the hydrogen kinetic energy distribution. While caging is negligible for the smallest clusters, it becomes more efficient upon increasing the cluster size, and for 12 solvent atoms the cage effect is already very strong. Finally, it is shown that while in the ground state the hydrogen atom points essentially toward the rare gas cluster, in excited librational states hydrogen is directed mostly away from argon atoms. As a consequence, caging of the photodissociating hydrogen atom in the case of a surface solvated HCl molecule can be efficiently "turned off" by librational preexcitation.