A specification of a routine name of a root of a call tree and a specification of a desired depth of call tree tracing are obtained. Upon entering a given routine in a program, a determination is made whether the given routine is the root. Responsive to determining that the given one of the routines is the root, trace information for the routine forming the root is output. Furthermore, upon entering a given one of the routines called, directly or indirectly, by the routine forming the root, a determination is made whether the given one of the routines called, directly or indirectly, by the routine forming the root of the call tree is within the desired depth from the routine forming the root of the call tree; and if this is the case, trace information is output for given one of the routines called, directly or indirectly, by the routine forming the root of the call tree.