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Memory Usage
CS-Studio/Phoebus is a plain Java application, with memory managed by the JVM. See also https://developers.redhat.com/articles/2021/09/09/how-jvm-uses-and-allocates-memory
When you launch the applications, the JVM option -Xmx sets the maximum amount of memory that the JVM will use, and -Xms sets the initial amount.
For example,
export JDK_JAVA_OPTIONS="-Xms500M -Xmx2G"
java -jar product.jar
will start the JVM will 500MB of memory, and it will allocate up to 2GB.
A tool like VisualVM (free, https://visualvm.github.io) or JProfiler (very good but not free, https://www.ej-technologies.com/products/jprofiler/overview.html) can be used to track memory usage over time.
What you should see is a sawtooth-type pattern where the application uses more and more memory, maybe up to the -Xmx limit, then frees it.
When you open several displays, the sawtooth pattern may ramp up more rapidly, and when you then close those displays, it should free memory and return to a slower/longer sawtooth pattern. If you find a scenario where the memory keeps increasing until running out of memory, you may have spotted a memory leak that should should report, ideally with a reproducible recipe.
It can be confusing to compare memory usage as reported by the JVM with the memory usage reported by the Linux OS.
Especially the "VIRT" virtual memory indicated in for example top may appear huge, but that tends to have no
practical significance, see for example https://stackoverflow.com/questions/561245/virtual-memory-usage-from-java-under-linux-too-much-memory-used, which also points to related discussions of the glibc MALLOC_ARENA_MAX setting.