What is a standalone CICS bundle?

What you've heard people refer to as standalone CICS bundles, are actually the original bundles. They, as their name suggests, stand alone, without needing other technology for support. They aren't actually called called standalone bundles though - this is just what some people refer to them as to differentiate between these bundles, and different bundles that arrived with the integration of cloud technology.

When cloud technology was introduced to CICS in version 5.1, different bundles were created. For example, application bundles, application binding bundles, platform bundles, and CICS bundles associated with these other bundles. These type of bundles relied on the CICS cloud technology, so the original type of CICS bundle became known as a standalone bundle. Both fulfill the same role, but non-standalone bundles rely of the cloud technology within CICS. Whereas, standalone bundles are their own entities and can be defined by CICS system definition (CSD) and system programming interface (SPI) commands.

Also, don't confuse them with OSGi bundles. Those are completely different!

For more information, check out Defining CICS bundles in the CICS Transaction Server for z/OS (CICS TS) documentation.