IBM High Level Assembler

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High Level Assembler or HLASM is IBM's current assembler programming language for its z/OS, z/VSE, z/VM and z/TPF operating systems on z/Architecture mainframe computers. There is also a version that runs on Linux, primarily intended for systems running on a z/Architecture system (this environment is sometimes referred to as Linux on IBM Z).


HLASM was released in June 1992 replacing IBM's Assembler H Version 2.[1][2] Despite the name, HLASM on its own does not have many of the features normally associated with a high-level assembler, but does offer a number of improvements over Assembler H and Assembler(XF), such as labeled and dependent USINGs, more complete cross-reference information, and additional macro language capabilities such as the ability to write user-defined functions. While working at IBM, John Robert Ehrman created and was the lead developer for HLASM[a] and is considered the "father of high level assembler".[4]

High Level Assembler Toolkit[edit]

The High Level Assembler Toolkit is a separately priced accompaniment to the High Level Assembler. The toolkit contains:[5]

  • A set of structured programming macros
    • DO/ENDDO
  • A disassembler.
  • A "Program Understanding Tool" (re-engineering aid).
  • A Source XREF utility (cross-reference facility).
  • Interactive Debug Facility.
  • Enhanced SuperC (source comparison tool).

See also[edit]


  1. ^ HLASM followed a SHARE requirement to incorporate Greg Mushial's enhancements[3] to Assembler H into the supported product.


  1. ^ IBM Corporation. "IBM High Level Assembler and Toolkit Feature - Release History". Retrieved October 21, 2012.
  2. ^ IBM Corporation (5 May 1992). "Announcement Letter 292-244: IBM HIGH LEVEL ASSEMBLER/MVS & VM & VSE". Retrieved October 21, 2012.
  3. ^ Greg Mushial (July 20, 1983), "Module 24: SLAC Enhancements to and Beautifications of the IBM H-Level Assembler for Version 2.8", SLAC VM NOTEBOOK, Stanford Linear Accelerator Center
  4. ^ "Guide to the John R. Ehrman collection". Online Archive of California. X5621.2010. Archived from the original on 2022-10-15. Retrieved 2022-10-15. [1]
  5. ^ IBM Corporation. "Toolkit Feature components". Retrieved October 21, 2012.

External links[edit]