If draining is enabled and requested conversations are taking too long to complete, an application program can try to terminate draining. A conversation already in progress is not interrupted, but the draining indicator can be changed. If the indicator is changed, queued conversation requests are not honored.

Application programs can alter the draining indicator by issuing an APPCCMD CONTROL=OPRCNTL, QUALIFY=CNOS macroinstruction with the appropriate draining indicator bits set off in the CNOS session limits control block. (In addition to the SLCDRAP bit, the SLCPARMS field contains the SLCDRAL bit, the source side draining indicator bit.)

If a CNOS request is issued that specifies a value of YES for the DRAINL parameter for a mode name with a session limit of 0 and draining is not enabled on the source side for that mode name, the macroinstruction is rejected with a parameter error indication.