STFLE Instruction for Dynamic Facility List Access
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Solution Overview
Problem
Existing information processing systems, such as those following the z/Architecture Principles, limit application programs from determining and utilizing available facilities due to the restricted issuance and accessibility of the STORE FACILITY LIST (STFL) instruction, which can only be executed by system-control programs and returns limited, fixed-length results that may not suffice for all applications.
Innovation Solution
The introduction of the STORE FACILITY LIST EXTENDED (STFLE) instruction allows application programs to dynamically determine and record the available facilities by specifying a storage location and data length, enabling more flexible and accessible facility information retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the STFL instruction is used to return facility information, then the information can be obtained by system-control programs, but application programs cannot execute the instruction due to privileged-operation program exception conditions
Solution Approach 1:
The patent introduces an intermediary mechanism where the operating system acts as a mediator between application programs and the facility information. The OS provides a system call interface that translates unprivileged application program requests into privileged STFL instruction executions, then returns the results to the application program. This resolves the contradiction by enabling application programs to access facility information without directly executing the privileged instruction.
Solution Approach 2:
The patent enables application programs to self-determine available facilities through the STFLE instruction, which allows them to specify their own storage locations and data lengths. This self-service capability eliminates the need for privileged operation intervention, allowing application programs to independently query facility information without requiring system-control program execution.
2Adaptability or versatility
If the STFL instruction returns fixed length and fixed definition data records, then the result format is standardized, but the information may not suffice for all application needs
Solution Approach 1:
The patent transforms the static fixed-length facility information format into a dynamic variable-length format. The STFLE instruction allows application programs to specify the desired data length and storage location, enabling the system to return exactly the amount of information needed. This dynamic approach resolves the contradiction by providing flexible information quantity that adapts to different application requirements rather than forcing a fixed format.
Solution Approach 2:
The patent changes the parameters of facility information retrieval by allowing application programs to specify storage location and data length as variables. Instead of receiving a fixed 32-bit record with fixed bit definitions, programs can now configure the exact parameters needed for their specific applications, resolving the contradiction between standardized format and application-specific flexibility.
3Reliability
If the STFL instruction is limited to supervisor state execution, then system integrity is maintained, but application programs cannot determine available facilities
Solution Approach 1:
The operating system serves as an intermediary that bridges the gap between application programs and privileged facility information. It provides a system call interface that maintains system integrity by executing the STFL instruction in supervisor state while still enabling application programs to access the information through a controlled interface. This resolves the contradiction by allowing application programs to determine available facilities without compromising system integrity.
Solution Approach 2:
The patent enables application programs to self-determine facility availability through the STFLE instruction executed in their own context. This self-service capability allows application programs to independently query which facilities are available on the system without requiring privileged operation intervention, resolving the contradiction between system integrity protection and application program capability.
4Ease of operation
If facility information is stored at a fixed real address, then direct access is possible, but portability across different operating systems is limited
Solution Approach 1:
The patent transforms the static fixed real address storage location into a dynamic variable location that can be specified by the application program. The STFLE instruction allows programs to choose their own storage location, eliminating dependence on OS-specific address mappings. This resolves the contradiction by enabling direct access to facility information while maintaining portability across different operating systems through user-defined storage locations.
Solution Approach 2:
The patent enables application programs to self-determine their own storage locations for facility information through the STFLE instruction. This self-service capability eliminates the need for OS-specific address conventions, allowing the same program to operate portably across different operating systems while maintaining direct access to facility information at the program-chosen location.
Data Source
AI summary
A method is provided for recording a list of facilities available to a program executing on an information processing system. In such method a storage location and a length of data are defined for recording the list of facilities by a program being executed on the information processing system. An instruction is issued by the program for determining the available facilities and recording the list of available facilities in accordance with the defined storage location and data length. A processor executes the instruction to determine the available facilities and record the list of facilities in accordance with the defined storage location and defined data length. The recorded list of facilities can then be read by the first program.