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1 MLEDUY commented Permalink

I would just summarize the USS component to show the full integration of CPLEX in the Mainframe environment and, which is a pity that I could not add the diagrams in your blog.

 
 
z/OS UNIX System Services (USS)
 
UNIX System Services is a Base Element in z/OS.
• UNIX System Services is X/Open UNIX 95 branded since 1996.
– Meet XPG 4.2 UNIX standards
• z/OS now supports the Single UNIX Specification, Version 3 (SUSv3).
– UNIX03 compliant
• UNIX System Services consist of:
– UNIX System Services Application Services (shell, utilities, and debugger)
– UNIX System Services Kernel
 
UNIX System Services Application Services (Shell, Utilities, and Debugger): Shell and Utilities provide the standard command interface familiar to interactive UNIX users. z/OS includes all of the commands and utilities specified in the X/Open Company's Single UNIX Specification, also known as UNIX 95 or XPG4.2. This feature allows your UNIX programmers and other users to interact with z/OS as a UNIX system without necessarily having to learn the z/OS command language or other interactive interfaces.
 
The z/OS UNIX Services Debugger provides a set of commands that allows a C language program to be debugged interactively. The command set is familiar to many UNIX users. UNIX
 
System Services Kernel: These services add the world of open UNIX-based computing to the z/OS operating system. With Language Environment, they support industry standards for C programming, shell and utilities, client/server applications, and the majority of the standards for thread management and the X/Open Single UNIX Specification. Application developers and interactive users using these interfaces can exploit the capabilities of z/OS without having to understand z/OS itself. The combination of open computing and z/OS allows the transparent exchange of data, easy portability of applications, cross-network management of data and applications, and the exploitation of traditional MVS system strengths in an open environment.
 
MVS Open Edition was implemented originally in MVS/ESA SP V4.3 with the POSIX standards. Many additional functions were added in MVS/ESA SP V5.2.2 to meet the XPG4.2 requirements. Later, support incorporated the full X/Open Portability Guide (XPG 4.2). OS/390 was awarded full UNIX 95 branding by the X/Open Group in 1996. USS, which began as UNIX95, is being extended to meet UNIX98 specifications and includes shell functions, numerous utilities, and UNIX file systems. z/OS USS, prior to 1.9, is registered as UNIX 95 compliant. z/OS 1.9 “better aligns” with UNIX 03, conforming to version 3 of the Single UNIX Specification (SUS). z/OS must support the Single UNIX Specification, Version 3 (SUSv3) standard in order to host new customer applications, facilitate porting, and enhance flexibility.
 
Today (April 2012), the latest z/OS version is z/OS 1.13 with an evolution of one release per year.
 
z/OS UNIX consists of the following:
 
• A system application programming interface (API)
The system API is a set of C language function calls and the operating system interfaces that support them. Some services are also accessible through assembler language.
• Shell and utilities
This is the interactive interface to z/OS UNIX services.
• A hierarchical file system
The hierarchical file system is a byte-oriented file system familiar to UNIX programmers.
• A debugger for UNIX (DBX)
The z/OS UNIX DBX debugger is an interactive tool for debugging C/C++ language applications that use z/OS UNIX services.
 
• System z File System (zFS) is the strategic UNIX Systems Services file system for z/OS
– The Hierarchical File System (HFS) functionality has been stabilized.
– HFS is expected to continue shipping as part of the operating system and will be supported in accordance with the terms of a customer's applicable support agreement.
• IBM intends to continue enhancing zFS functionality, including RAS and performance capabilities, in future z/OS releases.
– All requirements for UNIX file services are expected to be addressed in the context of zFS only.
 
A zFS file system is a named entity that resides in a zFS aggregate. The aggregate is a Virtual Storage Access Method Linear Data Set (VSAM LDS) and is a container that can contain one or more zFS file systems.
 
• Up to 33% improved performance
– Long-running I/O jobs
– Sequential reads of large files
– Random I/Os
• Improved recovery
– Immediate asynchronous write to disk
• Easy to implement
– Same UNIX APIs; no recompiles required
• Other features:
– zFS sharing across a sysplex for compatibility
– Disk space sharing between file systems in the same data set
– File system cloning
• Complementary to HFS
 
 
A user can interact with z/OS UNIX using the following interfaces:
 
• The application programming interface (API) consists of C function calls that can be used by C/C++ programs to access z/OS UNIX services. Java is also supported here.
The callable services can be used directly by assembler programs to access z/OS UNIX services, for example, to access files in the hierarchical file system. This possibility allows other high-level languages (excluding C) and Assembler to use z/OS UNIX services.
 
• The interactive interface is called the z/OS UNIX shell. More than one shell is supported. Users should be aware that the tcsh shell also is available.
 
The z/OS UNIX file system can be accessed by using any of the following:
 
• TSO/E has commands for browsing and editing HFS files, copying data between HFS files and z/OS data sets, mounting file systems, and invoking the z/OS UNIX shell. There is also a command called ISHELL which provides an ISPF menu-driven interface to the file system.
 
• JCL provides keywords which support the specification of HFS path names.
 
• REXX has a set of z/OS UNIX extensions (syscall commands) to access z/OS UNIX callable services.
 
• z/OS UNIX shell is the UNIX interface to the file system. It contains commands and utilities to access HFS files.
C programs. z/OS UNIX supports many C functions to access HFS files.
 
• Shell scripts are similar to REXX execs. z/OS UNIX shell commands and utilities can be stored in a text file which can be executed.

2 JeanFrancoisPuget commented Permalink

Michel,

 
thank you very much for the detailed comment.
 
Let me see how to add figures, this bligging platform is new to me (even if I did post something three years ago!)