Description:
The ledger size increases when there are unacknowledged messages on the subscriber side. When a publisher ledger file size has unacknowledged messages, it will try to resend those messages periodically and this will result in high memory usage.
Symptoms:
Growing ledger size increases when there are unacknowledged messages from the subscriber side.
Cause:
Messages are held in the ledger for two reasons:

When a message is confirmed, it is not actually deleted from the ledger, rather it is marked for deletion. The ledger file management is dependant on the O/S call "ftruncate".  When the O/S needs resources, the memory space will be reclaimed. You may wish to examine the ledger file and note that messages are being confirmed in a timely manner, but the shrinking of the ledger file is O/S dependant unless messages are not being confirmed.

When running multiple TIBCO IntegrationManager™ (IM) Engines, verify with each of the publishers and subscribers whether the messages and confirmations are reaching in a timely manner.

Growing ledger causes a memory increase for TIBCO IntegrationManager™ Engines.