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DEALLOC - Free Storage Print E-mail
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Written by Chamara Withanachchi   
DEALLOC(EN) pointer-name

The DEALLOC operation frees one previous allocation of heap storage. pointer-name is a pointer that must be the value previously set by a heap-storage allocation operation (either an ALLOC operation in RPG, or some other heap-storage allocation mechanism). It is not sufficient to simply point to heap storage; the pointer must be set to the beginning of an allocation.


The storage pointed to by the pointer is freed for subsequent allocation by this program or any other in the activation group.


If operation code extender N is specified, the pointer is set to *NULL after a successful deallocation.


D Ptr1            S               *
D Fld1            S              1A
D BasedFld        S              7A   BASED(Ptr1)
 
 /FREE
    // 7 bytes of storage are allocated from the heap and
    // Ptr1 is set to point to it
    Ptr1 = %alloc (7);
     // The DEALLOC frees the storage.  This storage is now available
    // for allocation by this program or any other program in the
    // activation group.  (Note that the next allocation may or
    // may not get the same storage back).
    dealloc Ptr1;
     // Ptr1 still points at the deallocated storage, but this pointer
    // should not be used with its current value.  Any attempt to
    // access BasedFld which is based on Ptr1 is invalid.
    Ptr1 = %addr (Fld1);
     // The DEALLOC is not valid because the pointer is set to the
    // address of program storage.  %ERROR is set to return '1',
    // the program status is set to 00426 (%STATUS returns 00426),
    // and the pointer is not changed.
    dealloc(e) Ptr1;
     // Allocate and deallocate storage again.  Since operational
    // extender N is specified, Ptr1 has the value *NULL after the
    // DEALLOC.
    Ptr1 = %alloc (7);
    dealloc(n) Ptr1;
 /END-FREE
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