1. An apparatus for managing one or more list data structures each comprising one or more list entries, within a Structured External Storage (SES) facility in a data processing system, said apparatus comprising, (a) one or more Central Processor Complexes (CPC's) each comprising a processing unit and main storage, each said CPC capable of executing one or more user processes; (b) said Structured External Storage (SES) facility coupled to each of the one or more CPC's; (c) communication means for communicating List Function requests by one or more user processes between one of said one or more CPC's and said SES; (d) detection means in said SES, responsive to said list function requests, for detecting a state change for one of said one or more list data structures Caused by performance of said list function requests; (e) registration means in said SES for registering interest of one of said user processes, executing on a particular one of said one or more CPC's, in said state change for a set of said one or more list data structures by associating an identifier of of a first process of said one or more user processes with a notification field with each list data structure in said set and transmitting a registration message comprising a process identified, a list identifier , and a vector means entry identifier to a registration process in said SES; (f) means in said SES utilizing Said registration message for communicating said state change notification from said SES to said particular one of said one or more CPC's over said communication means, and means in said particular one of said one or more CPC's receiving said state change notification for directly updating said notification field to indicate that said state change has occurred.