Refreshing changed data

You can refresh blocks that are mapped to either a temporary object or to a permanent object. You must identify the object and specify the range of blocks you want to refresh. When you refresh blocks mapped to a temporary object, window services replaces, with binary zeros, all changed blocks that are mapped to the window. When you refresh blocks mapped to a permanent object, window services replaces specified changed blocks in a window or in the scroll area with corresponding blocks from the object on DASD.

To refresh an object, call CSRREFR. For a description of CSRREFR parameters and return codes, see CSRREFR — Refresh an object.

To identify the object, you must supply an object identifier for object_id. The value supplied for object_id must be the same value CSRIDAC returned in object_id when you requested access to the object.

To identify the blocks of the object that you want to refresh, use offset and span. The values assigned to offset and span, together, define a contiguous string of blocks in the object:

The value assigned to offset specifies the relative block at which to start. An offset of 0 means the first block; an offset of 1 means the second block; an offset of 2 means the third block, and so forth.
The value assigned to span specifies the number of blocks to save. A span of 1 means one block; a span of 2 means two blocks, and so forth. A span of 0 has special meaning: it requests that window services refresh all changed blocks to which a window is mapped, or that have been saved in a scroll area.

Window services refreshes each block within the range specified by offset and span providing the block has changed and a window or a scroll area is mapped to the block. At the completion of the refresh operation, blocks from a permanent object that have been refreshed appear the same as the corresponding blocks on DASD. Refreshed blocks from a temporary object contain binary zeroes.