Copyright 2020 - BV TallVision IT

So is there no way to get access to the variables of a calling program (program that called you) ?

In some (rare) cases a user exit that SAP has made available simply does not supply enough information. In debugging you discovered that the information you need is available before the user exit or function module is called. Define a FIELD-SYMBOLS variable and assign the variable to the one you need - from the other (older) dimension.

Like so:

CONSTANTS: co_ACCESSMAKER(20) TYPE C 
  value '(SAPLV60A)VBRK'.
FIELD-SYMBOLS: <fs_VBRK> type VBRK.

assign (co_ACCESSMAKER) to <fs_VBRK>.

Or more simplified (and for a field rather than a whole work area)

FIELD-SYMBOLS: <fs_value_days> TYPE VBRK-VALTG.
ASSIGN ('(SAPLV60A)VBRK-VALTG') TO <fs_value_days>.

The report name SAPLV60A will tell the assign which area to fetch the data from. Please beware: it is also possible to change values this way. If something does go wrong, it will be an impossible puzzle for the developer that needs to solve it. Like a sudoku puzzle, with number 5 in the very center, and no other numbers at all. He/she and a couple of ugly friends will await you in the car park.