db2 connect to <db_name>

To find out the maximum numbers of active connections that a database support type:

db2 get db cfg | grep -i MAXAPPLS

the output will be something like that:

 Catalog cache size (4KB)              (CATALOGCACHE_SZ) = (MAXAPPLS*4)
 Max number of active applications            (MAXAPPLS) = 250

If you want to check the instance level configuration for the maximum number of connections:

db2 get dbm cfg | grep -i max

 Max number of existing agents               (MAXAGENTS) = 400
 Max number of coordinating agents     (MAX_COORDAGENTS) = (MAXAGENTS - NUM_INITAGENTS)
 Max no. of concurrent coordinating agents  (MAXCAGENTS) = MAX_COORDAGENTS
 Max number of client connections      (MAX_CONNECTIONS) = MAX_COORDAGENTS
 Number of pooled fenced processes         (FENCED_POOL) = MAX_COORDAGENTS

To discover the high water mark for database connections , type the command below:

db2 get snapshot for dbm | grep -i high

the output will be something like that:

Private Sort heap high water mark              = 38238
High water mark for agents registered          = 129
High water mark for agents waiting for a token = 0
High water mark for coordinating agents        = 126
       High water mark (bytes)                 = 1114112
       High water mark (bytes)                 = 2342912

In this example you can notice the database supports 250 active applications and the High water mark was 129 of  the active connections.