SSI(nnn) - Subsystem Interface Definition
The SSI(nnn) statement specifies whether tracing is available for individual subsystem interface function definitions. Specify nnn as a number (1-256); see z/OS MVS Using the Subsystem Interface for the SSI number.
Note: If you modify SSI(nnn) parameter values and then restart JES2
with a hot start, the parameter values in effect before termination will be
used.