Abstract <p>The entropy of microscopic configurations accompanied hadron production in nucleus-nucleus collisions is discussed. It is expressed, in the <i>z</i>-scaling approach, via the momentum fractions of colliding particles and scattered constituents fragmented to produced particles, the structural and fragmentation fractal dimensions, the multiplicity density of negative particles and model parameter interpreted as a specific heat of nuclear medium. Principle of the maximal entropy with taking into account momentum conservation law for constituent sub-process is used to determine the momentum fractions and model parameters by requiring self-similarity of the function ψ in dependence on dimensionless variable <i>z</i>. Statistical interpretation of the entropy in terms ensemble of fractal configurations of internal structures of colliding hadrons and fractal configurations corresponding to a fragmentation process in the final state is given. A conservation law of a quantum cumulativity and quantization of fractal dimensions are formulated.</p>