Last month, IBM announced IBM z17, a next-generation mainframe powered by a robust AI infrastructure. By harnessing AI, IBM is transforming the mainframe experience, driving productivity gains for developers, operators and business users.. To fully exploit the innovations of new mainframe technology like z17 requires software and compilers to be at current versions. For example, getting to the latest version of COBOL, Enterprise COBOL 6.5, also announced last month, is necessary to exploit all the AI innovations available.  To accelerate that journey, IBM has introduced the COBOL Upgrade Advisor for z/OS to help businesses upgrade to IBM Enterprise COBOL for z/OS 6 with automated analysis and reporting using a modern VS Code interface (generally available 9 May 2025).

COBOL 6.5 fully supports the IBM z17 architecture to optimize application performance, and provides new features to help clients modernize their business-critical applications to propel forward with their digital transformation plans. 

New capabilities in Enterprise COBOL for z/OS 6.5 include:

• Support for the latest IBM z17 architecture, to reduce CPU utilization and operating costs

• IBM z17 introduces new hardware features designed to improve the performance of COBOL workloads. Enterprise COBOL for z/OS 6.5 introduces the ARCH(15) option, allowing you to generate application code to leverage the latest IBM z17 hardware architecture.

• When you upgrade to version 6 of this compiler from a previous version of the compiler, IBM recommends that you use the Enterprise COBOL for z/OS 6.5 NUMCHECK compiler option to identify invalid data for packed and zoned decimal data items. Because this option has performance impacts, IBM recommends a second compile with NONUMCHECK before deploying to production. If an additional recompile is not feasible, application performance may be impacted.

• When using the NUMCHECK compiler option, IBM Enterprise COBOL for z/OS 6.5 exploits the latest IBM z17 hardware enhancements and can reduce CPU usage by 14% on average when running compute intensive applications vs applications originally built with Enterprise COBOL for z/OS 6.4.[1]

• Running on IBM z17, IBM Enterprise COBOL for z/OS 6.5 exploits the latest IBM z17 hardware enhancements and can reduce CPU usage by 64% on average when running compute intensive applications vs applications built with Enterprise COBOL for z/OS 6.4 with:

  ·        COMP-5 data items

  ·        COMP, BINARY or COMP-4 data items when the TRUNC(BIN) compiler option is set.

• NoSQL database (VSAMDB) support to help you modernize your mission-critical COBOL applications

• Enterprise COBOL for z/OS 6.5 has historically supported relational databases such as IBM Db2 and IBM IMS. Enterprise COBOL for z/OS 6.5 introduces support for a modern, unstructured NoSQL database (VSAMDB), which until now has not been easily accessible in COBOL. NoSQL databases enable the storage and querying of data outside the traditional structures found in relational databases. They are designed to store data in a flexible manner, allowing for easier adaptation to evolving data structures and rapid application development. NoSQL databases are well-suited for storing and managing diverse data formats.

• Enterprise COBOL for z/OS 6.5 supports reading, writing, updating, and deleting of JSON documents in a VSAMDB file using COBOL’s file processing statements. This function is compatible with IBM EzNoSQL for z/OS data.

• You can connect to a flexible and easily maintainable EzNoSQL database (VSAMDB) directly from COBOL. You can access the same data through both IBM EzNoSQL for z/OS (which provides modern Python, Java, C, assembler APIs to VSAMDB) and IBM Enterprise COBOL for z/OS 6.5 support for VSAMDB. Applications can share a NoSQL database (VSAMDB) between Python, Java, C, assembler and COBOL programs. These programs can all read, write, update, and delete the same JSON document in a VSAMDB file.

• User-defined types support, to extend the functionality of existing business-critical applications and improve code modularity

• User-defined types, which are common in other programming languages are now available in Enterprise COBOL for z/OS 6.5. These user-defined type definitions act like templates that can then be reused, using the TYPE clause, to define new data items. The new data item acquires all the characteristics of the user-defined type. User-defined types are elementary or group items defined in the WORKING-STORAGE, LOCAL-STORAGE, LINKAGE or FILE section of a program, using the TYPEDEF clause.

• User-defined types can help save you time and minimize source code because you don't have to redefine complex data structures that occur as part of the definition of two or more data items within your program. All you need to do is create one definition, and apply it to any subsequent definitions of the same type that you might need.

• SMARTBIN (binary metadata) - invest in your future so that modules you compile today can take advantage of future IBM Z hardware enhancements and reduce operating costs, without having to be recompiled

• For applications that are not in active development and do not get recompiled regularly, you can avoid the need to recompile to get performance gains. Enterprise COBOL for z/OS 6.5 produces binary metadata by default so that code recompiled today can be optimized by IBM Automatic Binary Optimizer for z/OS in the future.

• The creation of smart binaries helps to improve integration with IBM Automatic Binary Optimizer for z/OS, including the latest ABO 2.3 which exploits IBM z17, also announced last month. Using IBM Automatic Binary Optimizer for z/OS 2.3 to optimize your COBOL 4.2 applications delivers comparable performance to applications compiled with IBM Enterprise COBOL for z/OS 6.5 without the need to re-compile or tune performance settings. [4]

• By combining ABO 2.3 for legacy binaries and Enterprise COBOL 6.5 for active development, you can maximize your return on investment (ROI) and take full advantage of the performance capabilities of IBM z17.

Features of Enterprise COBOL for z/OS made available through continuous delivery

Enterprise COBOL for z/OS supports the continuous delivery (CD) model. Through continuous delivery, new features and enhancements are included in Program Temporary Fixes (PTFs) along with corrective and preventative service. You receive new features and enhanced capabilities as soon as the code is ready. You benefit in receiving enhancements in a faster and more continuous way without waiting for the next release. Enterprise COBOL for z/OS 6.5 includes all of the V6.4 features delivered through continuous delivery. For a list and description of these features, refer to What is new in Enterprise COBOL for z/OS 6.4 and COBOL 6.4 with PTFs installed

How to Get Started:

COBOL 6.5 will be available on Shopz on June 13, 2025. Your IBM representative is available to assist you with any questions.

Full announcement letters:

• IBM Enterprise COBOL for z/OS 6.5

• IBM Enterprise COBOL for z/OS Value Unit Edition 6.5

Disclaimers:

[1] The performance improvements are based on the geometric mean of IBM internal measurements on IBM z17 running a z/OS 3.1 LPAR with 1 CP and 80GB Central Storage. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.5 use the options NUMCHECK, ARCH(15), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.4 use the options NUMCHECK, ARCH(14), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST.  The NUMCHECK compiler option helps detect invalid data for packed and zoned decimal data items. Performance results for customer applications will vary, depending on the source code, the compiler options specified, and other factors. 

[2] The performance improvements are based on the geometric mean of IBM internal measurements on IBM z17 running a z/OS 3.1 LPAR with 1 CP and 80GB Central Storage. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.5 use the options ARCH(15), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.4 use the options ARCH(14), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST.  Performance results for customer applications will vary, depending on the source code, the compiler options specified, and other factors. 

[3] The performance improvements are based on the geometric mean of IBM internal measurements on IBM z17 running a z/OS 3.1 LPAR with 1 CP and 80GB Central Storage, IBM z16 running a z/OS 2.4 LPAR with 1 CP and 80GB Central Storage, IBM z15 running a z/OS 2.4 LPAR with 1 CP and 80GB Central Storage, IBM z14 running a z/OS 2.3 LPAR with 2 CP and 128GB Central Storage IBM z13 running a z/OS 2.3 LPAR with 1 CP and 64GB Central Storage, and IBM zEC12 running a z/OS 2.2 LPAR with 2 CP and 64GB Central Storage. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.5 use the options ARCH(15), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.4 use the options ARCH(14), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.3 use the options ARCH(13), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.2 use the options ARCH(12), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. All benchmarks compiled with IBM Enterprise COBOL for z/OS 5.2 use the options ARCH(11), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. All benchmarks compiled with IBM Enterprise COBOL for z/OS 4.2 use the options OPT(FULL), LIB. Performance results for customer applications will vary, depending on the source code, the compiler options specified, and other factors. 

[4] The performance improvements are based on the geometric mean of IBM internal measurements on IBM z17 running a z/OS 3.1 LPAR with 1 CP and 80GB Central Storage. The COBOL 4.2 application optimized using IBM Automatic Binary Optimizer for z/OS 2.3 produced results within 2.4% of the same application compiled with IBM Enterprise COBOL for z/OS 6.5. All benchmarks optimized with IBM Automatic Binary Optimizer for z/OS 2.3 use the new ARCH(15) option and default settings for all other options. The input COBOL benchmarks modules optimized by IBM Automatic Binary Optimizer for z/OS were all compiled by Enterprise COBOL 4.2. All benchmarks compiled with IBM Enterprise COBOL for z/OS 4.2 use the options OPT(STD), LIB. All benchmarks compiled with IBM Enterprise COBOL for z/OS 6.5 use the options ARCH(15), OPT(2), STGOPT, AFP(NOVOLATILE), HGPR(NOPRESERVE), and LIST. Performance results for customer applications will vary, depending on the source code, the compiler options specified, and other factors.