There are multiple sources for finding middleware and solutions for Linux. As the web sites get updated this may change – let me know then I adapt the description.
Please note that none of those catalogs is complete, they are all snapshots.
Validated Open Source Software
The table below provides up-to-date information on open source packages that have been ported and/or validated on corresponding distro versions by IBM.
IBM Software product compatibility
The most important reports are the operating system reports. But you can also select a specific software and check the support for an operating system.
IBM System z page (unfortunately discontinued by IBM end of 2013)
This page lists the ISV solutions updated in approximately the last year.
Red Hat Product Catalog
All the products registered with Red Hat for RHEL. Unfortunately Reds Hat has removed the platform information. By now (2023) this is of limited use.
SUSE Linux Enterprise Software Catalog
SUSE has a catalog that can be searched quite easily. Make sure you select “System z” under architecture.