ORA-12537: TNS:connection closed' Errors Connecting To Oracle11g R1 on Linux via Oracle Net

ORA-12537: TNS:connection closed' Errors Connecting To Oracle11g R1 on Linux via Oracle Net

Suddently unable to connect to Oracle11g R1 (11.1.0.6) on Linux x86 via Oracle Net (i.e. using the TNS Listener).  The Oracle11g database instance is up but client cannot connect as listener service refuses connections.
sqlplus system/<password>@11gtest
SQL*Plus: Release 11.1.0.6.0 - Production on Fri Aug 22 11:59:54 2008
Copyright (c) 1982, 2007, Oracle. All rights reserved.
ERROR:
ORA-12537: TNS:connection closed
Corresponding error stack in the listener.log:

TNS-12518: TNS:listener could not hand off client connection
TNS-12547: TNS:lost contact
TNS-12560: TNS:protocol adapter error
TNS-00517: Lost contact
Linux Error: 32: Broken pipe

Cause:
Oracle user's stacksize was set to unlimited.

Solution:
To implement the solution, please execute the following steps:

1) Check the stacksize for the Oracle user to see if it is set to 'unlimited'
$ ulimit -a
For example:
ulimit -a
time(cpu-seconds) unlimited
file(blocks) unlimited
coredump(blocks) 0
data(kbytes) unlimited
stack(kbytes) unlimited <lockedmem(kbytes) 32
memory(kbytes) unlimited
nofiles(descriptors) 1000
processes 2047

2) If the stacksize for the Oracle user is set to 'unlimited', set the stacksize for the Oracle owner to 10240 kbytes.

For example:

ulimit -s 10240

Reference metalink Doc ID 733737.1