Abstract: The present invention relates to a polyvinyl chloride- based unplasticized molding composition which includes vinyl chloride homo-, co- and/or ter-polymer and/or mixtures or alloys thereof having a vinyl chloride or PVC content of more than 70% by weight, preferably more than 85% by weight, and 15 to 0% by weight of at least one impact-modifying polymer, which unplasticized molding composition includes, per 100 parts by weight of the PVC mixture if appropriate, pigments, colorants, lubricants, blowing agents, flame retardants, fillers, reinforcing fibers or other processing auxiliaries and the following additives:(a) 0.01 to 3 parts by weight of at least one calcium carboxylate,(b) 0.01 to 3 parts by weight of at least one zinc carboxylate,(c) 0.01 to 3 parts by weight of at least one organic co-stabilizer selected from at least one .beta.-diketone, at least one organic phosphite and/or at least one dihydropyridine, and(d) 0.