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Article Q40188
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FRE(-2) Returns Fixed Lowest Value Even After Stack Shrinks - Q40188
The FRE(-2) function returns in bytes the amount of unused stack space
available for the program.
However, when the stack-space allocation decreases, the value returned
by FRE(-2) stays fixed at the smallest size that was unused by the
stack up to that point of program execution. In other words, the
values successively returned by FRE(-2) never increase -- they either
decrease or stay the same.
More Information:
The first sample program included below demonstrates this behavior.
The example given is a recursive subprogram that reports the value of
FRE(-2) on the way down and back up through 10 levels of subprogram
recursion. As the stack space increases with the level of recursion,
the value of FRE(-2) decreases as expected. However, as the stack
space decreases with lower levels of recursion, the value reported by
FRE(-2) stays "bottomed out" at the lowest value reached during
recursion.
The only way to reset the "bottomed-out" value returned by FRE(-2) is
to end the program or execute a CLEAR statement. Note: The CLEAR
statement erases all variables and closes all files. In some cases, as
shown in Example 2, adding an INPUT statement before the FRE(-2)
statement allows FRE(-2) to go back up. Adding INPUT does not help
Example 1.
Example 1 demonstrates a case in which FRE(-2) goes down and stays
down: ◄See Example 1►
Example 2 demonstrates a case in which adding an INPUT statement
lets the value returned by FRE(-2) go back up:
◄See Example 2►