There is the following explanation in the help for the CTRANLOG command:
FIELD
Tran
The name of the transaction. If the transaction name is followed by a "+", then the record has been truncated.
If the transaction name starts with a "+", then the record is a continuation record from a previously truncated record.
The transaction is highlighted if the entry contains an abend, exception, or threshold information.
So the transaction +LSMM is a continuation of the LSMM+