1. A computer program product for determining an execution order of programs in a computer system, wherein the computer program product comprises a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause operations, the operations comprising: providing a dependency file indicating for each calling program at least one called program called by the calling program, wherein a called program that calls another program also comprises a calling program; processing the dependency file to determine an order in which the called programs are called by the calling programs; receiving a call to invoke one of the calling programs; determining from the order the called programs called by the calling program in response to receiving the call; invoking the determined called programs according to the order; and invoking the calling program in response to invoking the determined called programs, wherein the order indicates the order in which the calling programs and the called programs are invoked, and wherein the order indicates to invoke the called programs before invoking the calling programs that invoke the called programs.