View source for IBM z/OS 2.1 compatibility issue

In Model 204 versions 7.5 and lower, Horizon TCP  applications sending data larger than 16K might get the following error:   
<p class="code">M204.1254: User language statement is invalid in this conversation state</p>                          
This error occurs under z/OS version 2.1 because the TCP Default Send Buffer Size (DefaultSndBufSize) was increased  to 65536 (from 16384 in earlier versions).

The solutions are as follows:
<ul>
<li><b>Model 204 v7.5:</b> <br />Apply zap 75Z226.</li>
<li><b>Model 204 v7.4:</b> <br />Currently fixed by zap 74Z4552.  Contact [[Contacting Rocket Software Technical Support|Technical Support]].</li>
<li><b>Model 204 v7.1 (and lower):</b> <br />Workaround: Set z/OS 2.1 TCP DefaultSndBufSize to 16384.</li>
</ul>