Availability of HIS-server for mainframe z/OIS 3.1 and 3.2?

Rob H.R. Lagerweij

Focusing strictly on 3270 terminal emulation significantly lowers your risk profile. Because the underlying 3270 data stream and TN3270E negotiation protocols are mature, frozen standards, your Host Integration Server will communicate seamlessly with the VTAM and TCP/IP stacks on z/OS 3.1 and 3.2. The core executable handling this traffic, tn3serv.exe, simply translates these standard incoming terminal requests without relying on the complex, version-dependent APIs required by database or message queuing connectors.

While technical functionality is practically guaranteed for standard 3270 sessions, the administrative reality of the Microsoft support matrix remains unchanged. If a rare protocol negotiation issue causes the TN3270 service to drop connections or crash, typically logging an Event ID 21 or Event ID 4001 in your Windows Event Viewer, Microsoft Support will still capture network traces and identify the uncertified target mainframe version. To prepare for any potential troubleshooting during your testing phase, ensure your diagnostic logging is correctly configured in the registry at HKLM\SOFTWARE\Microsoft\Host Integration Server\Trace\TN3270 before migrating. Moving forward with z/OS 3.1 for terminal emulation is a highly stable technical path, provided your IT compliance policies permit operating outside the officially documented vendor matrix for that specific workload.

Hope this helps. :)

VP

Hi Rob H.R. Lagerweij,

Microsoft Host Integration Server 2020, even with its latest Cumulative Update applied, officially supports up to IBM z/OS 2.3. Microsoft has not published a certification timeline for z/OS 3.1 or 3.2. Because HIS relies on highly standardized communication protocols like DRDA for database integration and TN3270 for terminal sessions, a direct connection from your Windows environment to a newer z/OS 3.1 partition will technically function without immediate issues.

Despite this functional compatibility, maintaining strict adherence to the vendor support matrix is critical for production environments. If your OLE DB Provider or MQ components throw an unexpected database error, such as a SQLCODE -313, or a connection failure logged via the SNA Trace Utility located at C:\Program Files\Microsoft Host Integration Server 2020\system\snatrace.exe, Microsoft Support will likely require you to reproduce the issue on z/OS 2.3 or older. I strongly advise keeping production workloads on certified IBM releases while testing z/OS 3.1 in an isolated development environment until a future update brings full vendor support.

Hope this answer brought you some useful information. If it did, please hit "accept answer". Should you have any questions, feel free to leave a comment.

VP