IAS supports 64-bit address space.
When using the -ilp32 command-line option (this is the default for COFF32 output file format), symbolic addresses are limited to 32-bit allocation (data4). IAS displays an error message when you attempt to use relocatable expressions at 64-bit allocations (data8).
This feature is fully defined in the IntelŪ ItaniumŪ Architecture Assembly Language Reference Guide.