If a program running in a subspace needs additional storage, you must determine whether that storage must be protected by the subspace. If the storage does not need subspace protection, the program can obtain it by using the STORAGE macro and requesting storage that is not eligible to be assigned to a subspace.

A program running in the subspace might use storage that is not protected by a subspace to share data with a program running in another subspace, or to provide access to parameter lists, data areas, or exits needed by an MVS™ service.

If the additional storage must be protected by the subspace, the application program must have the server program obtain storage on its behalf. The server program can use the surplus storage that it obtained (described in Obtaining storage for subspaces). If none is available, the server program:

1. Makes a request for more storage meeting the requirements described in Storage attributes
2. Makes the storage range eligible to be assigned to a subspace by specifying the range on IARSUBSP IDENTIFY
3. Assigns the storage to the subspace by specifying the storage range and the subspace STOKEN on the IARSUBSP ASSIGN request.

After doing so, the server program can pass control back to the application program, which can then use the additional storage.

Keep in mind that the server program should preserve the starting address and number of pages of any additional storage that it obtains, to disassociate the storage and make it ineligible to be assigned to a subspace when the application program has finished processing, and to release the storage.