Use the STORAGE macro to request storage for your subspaces. You can also use the GETMAIN macro, but STORAGE is easier to use and has fewer restrictions and requirements than GETMAIN.

When the STORAGE macro successfully obtains storage, it returns the length and address of the storage. You supply the length and address of the obtained storage in a range list when you invoke the IARSUBSP macro to make the storage eligible to be assigned to a subspace. (Making storage eligible is described in detail in Making a range of storage eligible to be assigned to a subspace.)