IBM Toolkit for Swift on z/OS, V4.2 Community Edition

We are pleased to announce a new release of IBM Toolkit for Swift on z/OS. IBM Toolkit for Swift on z/OS, V4.2 introduces several Swift 4.2.1 compiler features, including z/OS specific updates. It is available as a no charge download here.

Swift 4.2.1 compiler updates

  • Support for running compile commands in parallel, resulting in faster build times by using -enable-batch-mode –j<#>
  • Conditional protocol conformances: allows types to conform to a protocol only when certain conditions are met
  • Compiler diagnostic directives similar to C/C++ (#warning, #error)
    #if !os(zOS) 
      #error "Library only supported on z/OS"
  • Compiler version directives. For example:
    #if swift(>=4.2) // Conditionally compile on Swift 4.2 or greater
  • Swift 4.2.1 implements a majority of the ABI binary compatibility features. Visit the Swift ABI dashboard for more information on ABI binary compatibility
  • Performance enhancements:
    • Changes in calling convention for retain/release cycle to reduce code size and improve runtime performance
  • For a complete list of Swift 4.2 features, visit

V4.2 z/OS specific updates:

  • Added support for EBCDIC 1140 encoding in Foundation library
  • Improved support for z14, use options: -Xcc -march=z14
  • New example of how to extend a 64-bit LE main application (written in PL/I) with a Swift library



We always look forward to hearing your feedback on the IBM Toolkit Swift on z/OS. You can report feedback via any of these methods:

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