This solution will work because global variable is visible on all stack levels (local variable is not).

But you'd use process private global varialble ^||pasp("unitcode") instead of  ^pasp("unitCode") which is visible from all processes and you can have collisons in multi user environment.

What about this one:

ClassMethod Indirection() [ ProcedureBlock = 0 ]{
 N (evenTotal)
 set TABLES(0)="EVEN" 
 set TABLES(1)="ODD"
 
 for i=1:1:100 {
   set table = TABLES((i#2)) 
   set @(table_"("_i_")")=i
   
   // Xecute alternative, same issue 
   ; set cmd = "set "_table_"("_i_")="_i 
   ; x cmd 
 }  set evenTotal=0
 set i="" for { set i=$ORDER(EVEN(i)) QUIT:i=""  
   set evenTotal = evenTotal+EVEN(i) 
 } 
 zwrite evenTotal}