Each Frame object represents a data frame within a tribal bot's call stack. A frame stores data relevant to a single RoboSpeak subprogram call. A stack frame is associated not with the code of a subprogram, but with a subprogram call that happens during a RoboSpeak program run.

Tribal bots' subprogram calls -- unlike methods in Scala -- don't have any parameters or local variables, and very little data needs to be stored in each CallStackFrame. In fact, only a single line number needs to be stored to indicate where the subprogram call was made (in order to determine where execution should resume once the bot returns from the subprogram).