What can a program do with a data space or a hiperspace?

Programs can use data spaces and hiperspaces to:

Obtain more virtual storage than a single address space gives a user.
Isolate data from other tasks in the address space.
Data in an address space is accessible to all programs executing in that address space. You might want to move some data to a data space or hiperspace for security or integrity reasons. You can restrict access to data in those spaces to one or several units of work.
Share data among programs that are executing in the same address space or different address spaces.
Instead of keeping the shared data in common areas, create a data space or hiperspace for the data you want your programs to share. Use this space as a way to separate your data logically by its own particular use.
Provide an area in which to map a data-in-virtual object.

You can place all types of data in a data space or hiperspace, rather than in an address space or on DASD. Examples of such data include:

Tables, arrays, or matrixes
Data base buffers
Temporary work files
Copies of permanent data sets

Because data spaces and hiperspaces do not include system areas, the cost of creating and deleting them is less than that of an address space.

To help you decide whether you need this additional storage area, some important questions are answered in the following sections. These same topics are addressed in greater detail in the appropriate sections in this document.

How Does a Program Obtain a Data Space or a Hiperspace™? Data spaces and hiperspaces are created through the same system service: the DSPSERV macro. On this macro, you request either a data space or a hiperspace. You also specify some characteristics for the space, such as:

Its size
Its name
Its storage key
Its fetch protection attributes

The macro service allocates contiguous virtual storage of the size (up to two gigabytes) you specify.

Who Owns a Data Space or Hiperspace? Although programs create data spaces and hiperspaces, they do not own them. When a program creates a data space or hiperspace, the system assigns ownership to the TCB that represents the program or to the TCB that your program chooses as the owner.

When a TCB terminates, the system deletes any data spaces or hiperspaces that the TCB still owns. If you want the space to exist after the creating TCB terminates, assign the space to a TCB that will continue to be active beyond the termination of the creating TCB.

Can Problem State Programs Use Data Spaces and Hiperspaces? Problem state programs can create and use both data spaces and hiperspaces. Some types of data spaces and hiperspaces require that a program be supervisor state or have PSW key 0-7.