Control-Flow Stack

description:: The ANS Forth standard says that it may not physically exist: > 3.2.3.2 Control-flow stack [...] > > If it does exist, it may be, but > need not be, implemented using the data stack. The format of > the control-flow stack is implementation defined. This means that the control-flow stack may exist only logically rather than both logically and physically. > Since the control-flow stack may be implemented > using the data stack, items placed on the data stack > are unavailable to a program after items are placed > on the control-flow stack and remain unavailable until > the control-flow stack items are removed. Equally placing new items onto the data stack blocks access to the control-flow stack items. A standard program cannot assume that the items left on the data stack are not modified, moved or removed while there are control-flow stack elements above them. See also: ../colon-sys