what is the equivalent of select max(column) in IDMS
The functionality of IDMS is totally different from DB2. DB2 is a relational database and IDMS is networked. IDMS record structure is like a linked list one occurence of record is attached to other. You can say one record occurence is equivalent to a single row in db2 table. however there is no such command which could let you know about your desired results in IDMS.
You need to go through each record occurence (say area sweep) and find out the maximum value by incorporating the logic in your program.