Catalyzes the production of pinosylvin from cinnamoyl-CoA and malonyl-CoA, and dihydropinosylvin from dihydrocinnamoyl-CoA. (E)-cinnamoyl-CoA + 3 H(+) + 3 malonyl-CoA = (E)-pinosylvin + 4 CO2 + 4 CoA 3-phenylpropanoyl-CoA + 3 H(+) + 3 malonyl-CoA = 4 CO2 + 4 CoA + dihydropinosylvin Optimum pH is 6-7. Phytoalexin biosynthesis; pinosylvin biosynthesis. Homodimer. By stress. Belongs to the thiolase-like superfamily. Chalcone/stilbene synthases family.