We hold 120 days in DDPAR, which as a data center bank has an incremental monthly cost (for retention >90 days). Additionally, we have developed an internal transaction research tool from our data warehouse to replicate history with 2-year visibility to augment research capabilities for research from statements.
One note on this – if your FI elects to update the DDPAR setting for a given product or account, the transactions at the time of transaction posting are coded with a transaction expiration Julian date (DDHIST/RETDAY), based on the value setting. Changing the DDPAR or account value will not update the historical transactions without programming intervention. Without programming to the transaction history items, there will be unintended consequences of either gaps in history if you are reducing the parameter value, or continued fall-off at an earlier date for past transactions if you are increasing the parameter value.