When you install isCOBOL, it asks you for the location of the Java installation, and saves this path in a file. Then all the executable wrappers installed in the %isCOBOL%/bin folder look for this file to find Java.
If you install a new version or type of Java (OracleJDK to OpenJDK, for instance), you just need to change the path saved in this file to redirect all of the wrappers to the new Java. This file is named and located in different place in the Windows and UNIX/Linux installations:
Change the java path in the "pref_jre.cfg" file (%ISCOBOL%.install4jpref_jre.cfg).
For example, in C:VeryantisCOBOL2020R1.install4jpref_jre.cfg, change the existing line
Change the java path in the "default_java.conf" file ($ISCOBOL/bin/default_java.conf).
For example, in /opt/isCOBOL2020R1/bin, open default_java.conf with vi, and change these lines: