Function module Global variables not cleared from memory?

Question

Hi,
This is may be simple & stupid question ( after posting  4242 posts ):)
" Declaration in TOP
data : begin of i_y1yatt occurs 0.
        include structure y1yatt.
data : end of i_y1yatt.
types: begin of t_yatt71.
       include structure yatt71.
types: tcode like sy-tcode.
types: dflag type c.
types: end of t_yatt71.
data : i_yatt71 type standard table of t_yatt71
               with default key  with header line  initial size 0.
This is code in the function module.
  loop at i_y1yatt.
    move-corresponding o_y1yatt to i_yatt71.
    if i_y1yatt-werks eq 'N501'.
       move space to i_yatt71-werks.
    endif.
    append i_yatt71. 
    " Here this internal contains the previous entry
    clear i_yatt71.
  endloop.
This function module is called 25 times in a minute.
My problem is this
For example : 1st tranmission is called this fm with 50 records,
and 2nd tranmission is called fm with 10 records.
My results are showing
last record in the 1st transmission is still on the memory while calling 2nd transmission.  ( Here in int table I_YATT71 still contains the 1st transmission's last records during the 2nd tranmission call)
As per my knowledge if each time calls comes in to fm all gloabl variables get cleared. but some how this not happening.
Anybody come across this scenario.
PS. I know i need to use clear statement within the loop as first statement.
a®

Answer 1

You must understand that when calling a FM, you load the entire function group into memory. IF there are global variables, then they are "alive" for the entire duration of the program execution. Meaning if you call the function numerious times, or even if you call another function within the same function group, the functions still have access to that same global variable space, so it must always be cleared manually by the developer at the required points.  You can not rely on the runtime to clear the global variables at the end of the function call.  So you should clear all you globals as the first operation in your function module call, if that is what is required.
Is this clear?
Regards,
Rich Heilman