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 computer system with a coupling facility is provided with a plurality of processors and a plurality of intersystem channels coupled to the processors via a memory bus. The coupling facility includes a memory bus interface for the memory bus and a plurality of channels for coupling said channels to said processors. The memory bus interface includes an adapter with at least two hardware vectors provided for command detection, command isolation, and parallel testing of the error states of the intersystem channels, one which detects a command vector arrival, and a second which contains error state vector indicators. A LOCATE CHANNEL BUFFER (LCB) instruction is employed which performs a sense and reset operation on the command vector to identify and isolate a new command, and subsequently reads a vector of said error states vector indicator to determine the presence or absence of link errors.

Abstract: A mechanism for communicating messages, each including a command and a response, in a network having central processing complexes (CPCs) and one or more coupling facilities. Each coupling facility has a central processor for executing instructions and a main storage. Messages are sent from a message control block in the main storage of the CPC sending the message, and the response to the message is received in a message response block of the CPC without an interrupt to the program being executed by the central processor of the CPC. Each message from a CPC to the coupling facility may include a command and an indicator bit which instructs the coupling facility to execute the command either in synchronism with or asynchronously to the execution of the sending processor. The coupling facility executes the command and returns a response which is received in a message response block of the main storage of the sending CPC without an interrupt to any program being executed by the central processor of that CPC.

Abstract: A message path mechanism in a network having central processing complexes (CPCs) joined by message paths to a coupling facility. The coupling facility locates message paths for sending messages from one CPC to another and for sending messages between the coupling facility and one or more of the CPCs. A message path status table is provided having an entry for each of the message paths. Each entry has an indicator indicating whether its message path is active or inactive. multiple connections between the coupling facility and systems in the CPCs are registered in the coupling facility. Also provided is a mechanism for validating that each message path is connected properly such that if a message path is disconnected and then reconnected to a CPC, the validation mechanism insures that the message path has been reconnected correctly.

Abstract: One or more central processing complexes (CPC's), each with one or more programs being executed, issue commands to a structured electronic storage (SES). The commands include ones that create or delete data structures in SES, and attach or detach users to the data structures. The commands include a comparative authority value operand and a new authority value operand. A data structure or user control information has an associated existing authority value. If the comparative authority value matches the existing authority value, the existing authority value is replaced by the new authority value, and the command is executed. If there is a mismatch, the existing authority value is returned to the program that issued the command, and the command is not executed in SES. This enables software to serialize management of SES and maintain a consistent view of objects in SES in the presence of faulty CPC's, without causing correctly operating CPC's to experience errors or undue delays.

Abstract: A Structured External Storage (SES) Facility is coupled to one or more Central Electronic Complex (CEC) Processors, each linked to each other in a System Processing Complex (Sysplex). Applications within a CEC communicate with the SES via messages over a communication means. The SES comprises one or more List Structures, each structure comprising one or more Lists, each List comprising a list control and none or more List Entries. List Entries may be keyed or unkeyed, have a List Entry Identifiers (LEID), created within the SES, and unique within a particular List Structure. List Entries may also have a unique (within a List Structure) Name, created and managed by the application. A plurality of List commands are provided for creating, locating, moving and deleting List Entries--with location reference possible by LEID, Name, Key, Location within List, or a combination of Key and Location within Key.

Abstract: One or more Central Processing Complexes (CPC), each with one or more programs being executed, become command initiators by issuing commands requesting an action to be performed by a command responder. The responder is a Structured Electronic Storage (SES) which comprises a coupling facility. The SES receives commands to be executed over a plurality of links interconnecting the CPC's and SES, and returns a response to the program that issued the command. The SES is the focal point for the CPC's to share data, control locks, and manipulate lists or queues. This couples the autonomous CPC's into a System Complex (Sysplex) displaying a single system image. An indicator associated with each of the links is set by SES when it appears to a initiator that problems on the link exist. The set state of any indicator prevents SES from starting execution of any subsequent commands.

Abstract: Two or more user applications executing on one or more processors, each controlled by an operating system, share use of a 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 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: One or more Central Processing Complexes (CPC), each with one or more programs being executed, become command initiators by issuing commands requesting an action to be performed by a command responder. The responder is a Structured Electronic Storage (SES) which comprises a coupling facility. The SES receives commands to be executed over a plurality of links interconnecting the CPC's and SES, and returns a response to the program that issued the command. The SES is the focal point for the CPC's to share data, control locks, and manipulate lists or queues. This couples the autonomous CPC's into a System Complex (Sysplex) displaying a single system image. An indicator associated with each of the links is set by SES when it appears to a initiator that problems on the link exist. The set state of any indicator prevents SES from starting execution of any subsequent commands.

Abstract: Apparatus and method insuring that data objects used to maintain state information for shared data at a local central processing complex (CPC) are coherent with respect to state information maintained at a structured external storage facility (SES) over a link is valid. An error detector is attached to the CPC side of the link for detecting errors on the link, and, when an error is detected, setting a error state pending (ESP) latch to indicate that the link has failed and that the shared data in the local data object may be invalid because a message invalidating the data may not have been received by the CPC. In data processing operations, the ESP latch is interrogated by a central processor in the CPC to determine the health of the message path to the SES facility. A local cache vector reflecting the validity of the shared data in the local cache may then be interrogated to determine if the shared data in the local cache is valid.

Abstract: A Structured External Storage (SES) device/processor is connected to two or more DP systems, thereby loosely coupling the systems. The SES is capable of holding data objects of two distinct types (List objects and Cache objects), and communicates commands and command responses with the systems using a message protocol. A support facility within a processor on which a system is executing receives status indications from the SES without interrupting mainline system execution. Within the SES, a serialization mechanism allows more than one command to execute in parallel without loss of data object integrity, or command consistency. A forward completion mechanism sends to systems early notification of completion of certain commands, without permitting results inconsistent with this notification to be obtained by the systems. And a restart mechanism permits interrupted commands to be restarted by the initiating system or, in certain cases, by another system.