# Guidelines for OpenVMS

This following topics provide information that is specific to OpenVMS platforms.

## Supported Platforms and Installation Packages

TIBCO Enterprise Message Service is available on the OpenVMS platform listed in the following table.

For supported versions and the latest changes, see the `readme.txt` file.

OpenVMS Distributions
Platform | Hardware Platform | Installer Package Suffix | Notes
--- | --- | --- | ---
OpenVMS | HP Integrity/Itanium, 32-bit | `vms_ia64.zip` | Supports the C client library only.

## Additional Information for OpenVMS Programmers

There is some additional information on compiling and multi-threading that can be useful to VMS programmers.

Compile

On OpenVMS platforms, EMS programmers must define the C-compile command appropriately.

For the VSI C compiler:

    $ CC :== CC/FLOAT=IEEE/IEEE_MODE=UNDERFLOW_TO_ZERO -
    /PREFIX=ALL/INCLUDE_DIRECTORY=("/tibems/include",[])

Link

EMS API libraries are multi-threaded, so OpenVMS scheduler upcalls can yield significant performance improvements:

    $ LINK/THREADS_ENABLE=UPCALLS

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