The SWAREQ macro

SWAREQ, instead of actually writing or reading information, only tells you the location of the SWA block that you are interested in. Once you know the location, you can read or write information yourself. By specifying a function code when you invoke the macro, you can request the following SWAREQ services.

• Read Locate — Returns the address of the block that you specify. It does not read any data from the specified block into your buffer. Your program does the actual reading by coding techniques such as MVC instructions.
• Write Locate — When you use regular coding techniques to write data from your buffer into the data area of a SWA block, the system does not know that the block has been written into. To allow the system to set up the control fields that are necessary to integrate the SWA block into the system, use write locate to inform the system that a write has taken place.