When you display RUNID, the scripting language displays it as a 10 digit integer.
The RunID value in the IDS table in SQLServer is datatype "int". This datatype is 4 bytes of storage, and has a maximum positive value of 2,147,483,647. This doesn't necessarily mean the Automic Workload Engine will support this high of a number though? I still don't know what the upper range might be.