Pointers can be passed and returned between C and PL/I routines. Because the C #pragma linkage(PLI) specifies that pointers, unlike other parameters, are passed directly, there is one level of indirection less on the PL/I side.

In order for PL/I to receive a pointer to a PL/I data type, C must pass a pointer to a pointer to the C data type. Conversely, if PL/I returns a pointer to a data type, C receives a pointer to a pointer to the data type.

Structures, arrays, and strings should be passed between C and PL/I only by using pointers.

The non-address bits in all fullword pointers declared in PL/I source code must always be zero. If they are not, results are unpredictable.