Subject: What does the statement ALLOCATE means in FORTRAN language?

Recently I've came across the statement - ALLOCATE & ALLOCATABLE in one of 
the programs in the FORTRAN programming language. I've tried to look for 
the function of these statement in FORTRAN books to no avail. Example of 
these statements are given below:-
      integer x[ALLOCATABLE](:) 
      ALLOCATE (x (1,z), STAT = ierror)
1) What is the meaning of ALLOCATE and ALLOCATABLE?
2) What is the function of these statements?
3) What are the significance of these function in a program?
4) What is the similar statement in C++ for these function?

I'm new to fortran programming language. So it would be very helpful if an 
example is given. 

Your help is help is very much appreciated.
Thank you.   

Re: What does the statement ALLOCATE means in FORTRAN language?