Abstract: Two or more user applications executing on one or more processors, each controlled by an operating system, share use of a list and subsidiary list structure within a Structured External Storage (SES) facility to which each processor is connected. One of the applications registers interest in particular state transitions affecting one or more subsidiary lists within the list structure, causing a process within the SES to notify the appropriate processor when a list operation causes the particular state transition, without interrupting processing on the processor. The application receives notice of the state transition by periodically polling a vector within the processor, or by receiving control when a test by the operating system of a summary indicator for the vector causes an application exit to be driven.

Abstract: A method and apparatus for optimizing a data structure of an external data storage facility shared by a plurality of data processing systems, the data structure being allocated by a first allocation command which includes first allocation parameters based on an amount of storage space in the external data storage facility assigned for creation of the data structure and a composition of the data structure, includes a device for determining values of the first allocation parameters, to thereby determine a first composition of the data structure, a device for determining an actual usage of the data structure, to thereby determine a second composition of the data structure, a device for comparing the first composition of the data structure with the second composition of the data structure, and a device for issuing, based on an output from the comparing device, a second allocation command having second allocation parameters, to the data structure for reallocation thereof.

Abstract: A Structured External Storage (SES) processor is linked by a communication means to one or more general purpose processors. Two or more applications executing on the one or more general purpose processors communicate function request messages to a message processor within the SES to effect serialized sharing of data within the SES. Within the message processor, a predicate function means executes unconditionally on receipt of one of the function request messages, and a data function means executes conditionally and atomically with respect to the predicate function means following a "successful" condition produced by the predicate function means.

Abstract: Computer system processing complexes which can operate actually or apparently synchronously and in parallel or asynchronously in a network have a coupling facility for sending and receiving commands, responses, and data. The memory for the central processing complexes (which is accessible to each of the processing elements) is provided with storage for messages and data for coupling over a communication channel interface. Each of a plurality of processing elements (CPC) has data objects used to maintain state information for shared data in the coupling facility storage. The coupling facility can receive both message commands and data, sending data and responses to messages, and sending and receiving secondary messages.