Values for the magnetic Gruneisen parameter gamma _M for CuMn, (Cu-10 at.% Al)Mn and AgMn alloys determined form low-temperature thermal expansion and specific heat capacity measurements are reported. mu _M is found to be both temperature- and concentration-dependent in contrast to the simple RKKY model for the spin-glass ordering. The concentration dependence of mu _M differs significantly from that reported earlier based upon a combination of thermal expansion and specific heat capacity measurements made independently on different samples. Dipolar anisotropy is discussed as a possible cause of the dependence of mu _M on temperature and magnetic impurity concentration.