The spaSize build descriptor option specifies the number of bytes in the IMS™ scratch-pad area (SPA). The default is 0.
If the program receives control from an IMSADF II program, the value of spaSize must be set to 28, which is the size of the IMSADF II SPA when the IMS ADF II work database is used. If the program receives control as a result of an IMS message switch but not from an IMSADF II program, the value of spaSize must be large enough to contain the required IMS SPA fields, the programs's input record, and a segmentation status byte.
See also spaStatusBytePosition and (if your program receives control from an IMSADF II program) spaADF.
For an overview of program switches, see Transfers among IMS MPPs.