IMS support includes two new transactions, /CIC and /IMS, that you use to switch enterprise servers to CICS and IMS modes respectively. In order for these new transactions to be available you need to update your resource definition file using the caspcupg command as root as follows:
caspcupg /rIMSIVP
See the section Adding IMS-specific Resource Definitions in the chapter Configuring MSS-enabled Enterprise Servers for IMS in your Mainframe Subsystem Support Configuration and Administration Guide for more information on the caspcupg command.