Specification limits are set by the user, not JMP, generally as an option in the Column Information/Properties section of each variable. The notion of a software program...any program Minitab, JMP or even the vaunted Excel, determining specification limits is nonsense. I suggest reviewing a good book on Statistical Process Control and Capability Analysis. A good place to start is Don Wheeler's Book, "Understanding Variation The Key to Managing Chaos."
For specifics on JMP's capabilities in this space I suggest perusing the JMP Online Documentation pertaining to Process Capability. Details for pathways to setting specification limits in JMP are within. You are running version 14...this documentation is for version 16 so some of what you see might not reside in your version...but the basics have been in JMP since probably version 4 or so...
Process Capability in JMP