z/OS 1.4 and z/OS 2.2 are far enough apart that there was never a single
IBM machine model that officially supported both releases. IBM supported
running z/OS 1.4 up to the z9 models, and z/OS 2.2 starts with the z10
models. If you've got them both running on one CEC, it's lucky, and
congratulations. Please make sure you're not running z/OS 1.4 in Bimodal
Accommodation (ESA/390 31-bit mode), by the way, for at least two big

With that background, I don't think you can or should assume a single CEC
"forever," or even for very long. At least, it'd be prudent not to "wire
in" such rigidity. If you're still nervous, you can set up both EE and CTCA
connections. I recommend configuring EE (over a HiperSocket if on the same
CEC) as primary/favored since the performance characteristics are likely to
be better, but you can backstop EE with CTCA if you wish.

EE officially debuted with OS/390 Version 2 Release 7 in early 1999, was
backported to OS/390 Version 2 Release 6, and was circulating in earlier
form before that. EE certainly wasn't fresh off the boat with z/OS 1.4,
which reached End of Service in 2007, over 8 years after EE debuted. z/OS
1.4 is plenty new enough for these purposes. I recall plenty of EE adoption
in z/OS 1.4 and prior.

Timothy Sipples
IT Architect Executive, Industry Solutions, IBM Z & LinuxONE,
E-Mail: sipp...@sg.ibm.com

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