Important points about the scratchpad area (SPA)

When program A passes control of a conversation to program B, program B needs to have the data that program A saved in the SPA in order to continue the conversation. IMS gives the SPA for the transaction to program B when program B issues its first message call.

The SPA is kept with the message. When the truncated data option is on, the size of the retained SPA is the largest SPA of any transaction in the conversation.

For example, if the conversation starts with TRANA (SPA=100), and the program switches to a TRANB (SPA=50), the input message for TRANB will contain a SPA segment of 100 bytes. IMS adjusts the size of the SPA so that TRANB receives only the first 50 bytes.