Setting the situation Persistence in the tacmd createSit command.
This has been identified as a document defect under APAR IV41494
Resolving the problem
This is possible and is supported.
It is set with the -p SitInfo parameter of "COUNT="<Situation Persistence Number>"
tacmd createsit -s <SITNAME> -b <BASENAME> -p SitInfo="COUNT=<Situation Persistence Number>"
This is not currently covered in the product documentation. A DOC APAR has been opened : IV41494