Flat-shaped composite material for manufacturing a package, comprising: - a polymer outer layer, - a polymer inner layer, - a fibrous support layer, which is arranged between the polymer outer layer and the polymer inner layer, - wherein the flat-shaped composite material has a plurality of fold lines, which are arranged and designed such that a closed package can be manufactured by folding the flat-shaped composite material along the fold lines and by connecting seam surfaces of the flat-shaped composite material, - a sleeve surface, wherein the sleeve surface comprises a front surface, a first side surface, a second side surface, a first rear surface and a second rear surface, - base surfaces, wherein the base surfaces comprise triangular base surfaces and quadrangular base surfaces (5"), and - gable surfaces, wherein the gable surfaces comprise triangular gable surfaces and quadrangular gable surfaces (6"), - wherein the base surfaces and the gable surfaces are arranged on opposite sides of the sleeve surface, - wherein the sleeve surface has at least one stress-relief surface (17A, 17B), which is arranged between the front surface and one of the two side surfaces (16A, 16B), - wherein a first sleeve fold line is provided between the stress-relief surface (17A, 17B) and the adjoining front surface, and - wherein a second sleeve fold line (18") is provided between the stress-relief surface (17A, 17B) and the adjoining side surface (16A, 16B), characterised in that the at least one stress-relief surface (17A, 17B) adjoins a quadrangular base surface (5") in the region of the base surfaces and adjoins a triangular gable surface in the region of the gable surfaces. - a polymer outer layer, - a polymer inner layer, - a fibrous support layer, which is arranged between the polymer outer layer and the polymer inner layer, - wherein the flat-shaped composite material has a plurality of fold lines, which are arranged and designed such that a closed package can be manufactured by folding the flat-shaped composite material along the fold lines and by connecting seam surfaces of the flat-shaped composite material, - a sleeve surface, wherein the sleeve surface comprises a front surface, a first side surface, a second side surface, a first rear surface and a second rear surface, - base surfaces, wherein the base surfaces comprise triangular base surfaces and quadrangular base surfaces (5"), and - gable surfaces, wherein the gable surfaces comprise triangular gable surfaces and quadrangular gable surfaces (6"), - wherein the base surfaces and the gable surfaces are arranged on opposite sides of the sleeve surface, - wherein the sleeve surface has at least one stress-relief surface (17A, 17B), which is arranged between the front surface and one of the two side surfaces (16A, 16B), - wherein a first sleeve fold line is provided between the stress-relief surface (17A, 17B) and the adjoining front surface, and - wherein a second sleeve fold line (18") is provided between the stress-relief surface (17A, 17B) and the adjoining side surface (16A, 16B), characterised in that the at least one stress-relief surface (17A, 17B) adjoins a quadrangular base surface (5") in the region of the base surfaces and adjoins a triangular gable surface in the region of the gable surfaces.