According to one exemplary embodiment, a method for establishing subsystem boundaries is provided. The method may include receiving an input program having a plurality of subroutines and at least one inter-subroutine call. The method may include generating a graph having a plurality of nodes and at least one edge, wherein the at least one edge includes a first end connected to a first node and a second end connected to a second node. The method may include assigning an edge weight to the at least one edge wherein the edge weight is based on a number of second ends received by the second node. The method may include determining, based on the assigned edge weight, a distance value between each pair of nodes. The method may include generating a grouping of nodes based on the determined distance value between each pair of nodes.