CICS® VT provides a 16k work area for passing data between exits. The address of the work area is in EXWRKA. In an IRD, the address is in IRDWRKA. Use this as a scratch pad area.
The work area is shared by all exits in the same DIM. For example, if your file has 3 FBEs and one IRD, the same 16k area is shared by all 4 exits.
If you need to use the work area, you must ensure that you implement a technique to avoid one exit overwriting an area that is required by another exit. One technique to do this is to have a single copybook which describes the entire area and is used in every exit.