Recently I updated to V7R4 and noticed that files I created using the JAR command were now being created with CCSID of 1208 vs 819 on V7R3 and previous.

If you require the JAR files to remain 819 you can set the PASE_DEFAULT_UTF8 environment variable to the value of "N" as shown in this article from IBM.

ADDENVVAR  ENVVAR(PASE_DEFAULT_UTF8) VALUE(N)

This caused me problems for one of my applications that uploads ZIP files created with the JAR command to the cloud since the files seem to work best with CCSID 1252 is used.  When the ZIP file had a CCSID of 1208 it would cause conversion errors when trying to upload them.