what is "multiple activations of a function"

[tao zhang]

i read the book <Press.Memory.as.a.Programming.Concept.in.C.and.C++>
chapter 5 say:
A function call can be implemented in various ways, depending on the strategy for allocation of the activation frame. If a static allocation is used (in Fortran, e.g.) then multiple activations of a function are impossible

i can't understand what's the meaning of "multiple activations".

thx all

[Cubbi]

It means "recursive call". In early versions of Fortran, functions could not be recursive.

[JLBorges]

> If a static allocation is used (in Fortran, e.g.)

AFAIK, this (static allocation of the activation record) is true for FORTRAN up to FORTRAN-77, not for FORTRAN-90 or later. See: http://www.cs.utsa.edu/~wagner/CS3723/storage/runtime.html

> multiple activations of a function are impossible

See: http://web.cs.wpi.edu/~kal/PLT/PLT12.3.6.html
http://www.ibiblio.org/pub/languages/fortran/ch1-12.html