The CSI option is the replacement for the VSAM option, and has been available since 2010.
After CA JCLCheck apar SO03601 and SO03602 are applied, informational message "CAY6570I VSAM OPTION IS OBSOLETE, DEFAULTING TO CSI" will be issued if the VSAM option is specified.
Referenced KB:
What is the difference in using the CSI or VSAM op - CA Knowledge