OPTIME is CICS's timeout which uses CICS code to timeout the user. OPTIME field is retrieved by CICS and times a user out based on its content.
Since TSS has its own timeout, OPTIME field is not used by TSS. LOCKTIME field is used for the Top Secret timeout.
OPTIME(0) will prevent a user from being timed out by CICS timeout/code.
Top Secret documentation updated to reflect OPTIME(0).