User spaces are objects that used for storing user-defined information. They are permanent objects that are located in either the system domain or the user domain. They have an object type of *USRSPC and a maximum size of 16MB. You can save and restore user spaces to other systems. If, however, the user spaces contain pointers, you cannot restore the pointers even if you want to restore them to the same system.
You can use the user space APIs to:
Create user spaces to be used by list APIs to generate lists of data.
Store large amounts of data. You can create a user space as large as 16 megabytes. You cannot create a data area larger than 2000 bytes.
Save information in user space objects, and save and restore the object with the information in it using CL commands.
Pass data from job to job or from system to system.
Note: If the allow user domain (QALWUSRDMN) system value contains only the QTEMP library, you can use only the user space APIs to create and manipulate user domain spaces in library QTEMP. You cannot use the Retrieve Pointer to User Space API
The user space APIs allow you to create and delete user spaces, change and retrieve the contents of user spaces, and change and retrieve information about user spaces.
For additional information, see Using User Space APIs.
The user space APIs are:
Change User Space (QUSCHGUS) changes the contents of a user space.
Change User Space Attributes (QUSCUSAT) changes the attributes of a user space object.
Create User Space (QUSCRTUS) creates a user space.
Delete User Space (QUSDLTUS) deletes user spaces created with the QUSCRTUS API.
Retrieve Pointer to User Space (QUSPTRUS) retrieves a pointer to the beginning of a user space for a high-level language (HLL) that supports pointers. HLLs that support pointers can use this pointer to manipulate the contents of a user space directly.
Retrieve User Space (QUSRTVUS) retrieves the contents of a user space. It does not retrieve descriptive information about the user space, such as its size.
Retrieve User Space Attributes (QUSRUSAT) retrieves information about creation attributes and current operational statistics of the user space, such as its size.