1) Use the TPDISP command to display applications that are connected.
APPLICATION NAME: ESPPROD_A
VTAM LU NAME: ESPTP1
DEFAULT LOGON MODE: TP62
LOCAL TRANSACTIONS: INTER_SYSTEM_JOB_TRACKING
------------ CHECKPOINT INFORMATION -----------
CHECKPOINT DSNAME: CYB.TP.CKPT
CHECKPOINT SIZE: 1474560 BYTES
CHECKPOINT USED: 720 BYTES
QUEUED APPLICATIONS: NONE
2) You can use the TPAPPL command which manages interactions with remote partner applications. So to stop the interaction with ESP_MV04 you would need OPER authority and enter the following.
OPER TPAPPL ESPPROD_B DELCONV
When you are ready to re-establish connection you would enter.
OPER TPAPPL ESPPROD_B ADDCONV