After using the MAP service, the application can access the data inside the window directly through normal programming techniques. When the application changes some data in the window, however, the data on the object does not consequently change. If the application wants the data changes in the window to appear in the object, it must use the SAVE service. SAVE writes, to the object, all changed blocks within the range to be saved inside the window. SAVE does not write unchanged blocks. When SAVE completes, the object contains any changes that the application made inside the virtual storage window. If a SAVE is preceded by another SAVE, the second SAVE will pick up only the changes that occurred since the previous SAVE.
Optionally, SAVE accepts a user list as input. To provide a user list, the application uses the SAVELIST service. SAVELIST returns the addresses of the first and last changed pages in each range of changed pages within the window. The application can then use these addresses as the user list for SAVE. The SAVE operation can be more efficient when using the list of addresses, so an application can improve its performance by using SAVELIST and then SAVE.
When specifying a user list and when a data space or hiperspace contains the window, the caller must use an STOKEN with SAVE to identify the data space or hiperspace.
If the application changes some data in a virtual storage window but then decides not to keep those changes, it can use the RESET service to reload the window with data from the object. RESET reloads only the blocks that have been changed unless you specify or have specified RELEASE=YES.