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Develop high-performing C/C++ applications and system programs on z/OS while maximizing hardware use and improving application performance

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The IBM® C/C++ for z/OS® compilers, including the classic z/OS XL C/C++ compiler and the newly introduced Open XL C/C++ for z/OS compiler, are advanced optimizing C and C++ compilers on z/OS that use IBM Z® features to produce high-performing business applications.

The z/OS XL C/C++ compiler supports embedded CICS® and SQL statements in C/C++ source, simplifying the operation of C/C++ within CICS and Db2® environments. To expedite the delivery of z/OS® applications, you can use IBM® Application Delivery Foundation for z/OS® in conjunction with XL C/C++.

Open XL C/C++ is fully based on the LLVM open source Clang infrastructure and supports current C/C++ language standards and the latest IBM z16™ servers. Open XL C/C++ is a no-charge add-on feature for users who have enabled z/OS XL C/C++ on z/OS 2.4 or later.

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Migrating to new LLVM and Clang compiler infrastructure

Benefits Increase return on investments

Use leading-edge compiler optimization technology with modern IBM Z to enhance the performance of C/C++ applications on the highly secure and resilient z/OS platform. This initiative helps expedite return on investments and mitigate both business and IT risks.

Reduce migration efforts for C/C++ applications to z/OS

Open XL C/C++ is fully based on the open-source Clang and LLVM technology framework, adhering to the C17/C18 and C++17 language standards. This approach aims to reduce migration efforts when transitioning C/C++ applications from distributed platforms to z/OS.

Enhance emerging technologies on z/OS

Open XL C/C++ helps extend modern z/OS languages and utilities such as Python, Node.js, Go, Java and IBM Z Open Automation Utilities (ZOAU) to enhance their functionality and build application packages to advance technology adoption.

New hardware capabilities without code change

Specify the architectural level for which the executable program's instructions will be generated. This allows for delivering hardware-level capabilities directly through compiler options without modifying source codes.

Learn more about using IBM z16 features

Supports z/OS UNIX System Services and z/OS batch

Get support for z/OS UNIX System Services and z/OS batch under 32-bit non-XPLINK, 32-bit XPLINK and 64-bit XPLINK compilation modes, which are ideal for existing z/OS applications and porting applications from distributed platforms.

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Integration with a core set of tools

Use this compiler to integrate IBM Developer for z/OS Enterprise Edition tools, a robust toolset for developing and maintaining IBM z/OS applications through the implementation of DevOps practices. This suite also encompasses IBM Debug for z/OS, offering debugging capabilities and code coverage for applications written in C/C++.

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Support for program diagnosis and debug

Increase programmer productivity and code generation with a cost-effective way of diagnosing potential language semantics adherence, including support for IBM z/OS Debugger.

Explore IBM z/OS Debugger Explore debug support

High-performance libraries

Use the Mathematical Acceleration Subsystem (MASS) and Open Basic Linear Algebra Subroutines (OpenBLAS) libraries for accelerated execution of math and algebra functions used in business analytics.

Explore high performance libraries with Open XL C/C++ Explore high performance libraries with z/OS XL C/C++

Advanced optimization technology

Use advanced compilation and optimization technology to improve application performance.

Improving performance with compiler options
Product comparison
Products Open XL C/C++ for z/OS

The latest advanced optimizing C and C++ compiler on z/OS supports the current C/C++ language standards with the open-source Clang interface for improved compatibility with distributed platforms.

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z/OS XL C/C++

An advanced optimizing C and C++ compiler on z/OS that supports Metal C and z/OS subsystems, such as CICS, Db2 and IMS.

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Clients licensed to z/OS XL C/C++ are entitled to Open XL C/C++ Monthly License Charge (MLC), optional priced feature of z/OS

Distribution channel

Web deliverable

Part of z/OS optional features

METAL C for system programming capabilities

Programming with Metal C

Support for embedded CICS and SQL statements

Programming with other products

Improves compatibility with distributed platforms

Explore supported Clang options

Supports current C/C++ language standards

Enhanced language standard support
Integrate with other products When you use z/OS XL C/C++, you can write programs that use the power of other IBM products and subsystems. Explore interaction with other IBM products IBM CICS Transaction Server for z/OS


You can use the CICS command-level interface to write C/C++ application programs. The CICS command-level interface provides data, job and task management facilities that are normally provided by the operating system.


Explore CICS documentation
Information Management System (IMS)

IMS and z/OS XL C/C++ together can coordinate error handling.

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IBM Db2 database

Both z/OS Language Environment and z/OS XL C/C++ provide an interface to the IBM Db2® Universal Database Licensed Program. An XL C/C++ program requests Db2 services by using SQL statements embedded in the program.

Explore Db2 documentation
Resources Migrating to Open XL C/C++

Interested in migrating to new LLVM and Clang compiler infrastructure? Discover migration tips to make the process of migrating from XL C/C++ to Open XL C/C++ easier.

AutoSIMD compiler optimization for z/OS XL C/C++ programs

Learn about the AutoSIMD optimization introduced in the z/OS 2.2 XL C/C++ compiler.

Fix list for z/OS XL C/C++

Check out a complete list of releases, refreshes, fix packs and interim fixes sorted by version for IBM z/OS XL C/C++.

Related products IBM XL C/C++ for z/VM

Use a high-performance compiler for developing complex C/C++ programs on z/VM.

IBM XL C/C++ for Linux

Learn how you can take advantage of a high-performance compiler for developing complex C/C++ programs on Linux on Power Systems.

IBM XL C/C++ for AIX

Take advantage of a high-performance compiler for developing complex C/C++ programs on AIX.

Explore the IBM Compiler family of products
Next steps

Download IBM Open XL C/C++ now or discover z/OS XL C/C++ by scheduling a no-cost 30-minute meeting with an IBM Z representative.

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