ACF2 Errors with JES2 Running Under JES3

Products

• ACF2
• ACF2 - DB2 Option
• ACF2 for zVM
• ACF2 - z/OS
• ACF2 - MISC

Issue/Introduction

ACF2 and JES3 running in a test system in an attempt to migrate from JES3 to JES2.
Attempting to startup JES2 under JES3, S JES2,SUB=JES3.
JES2 will start but are experiencing issues accessing the system through TSO or other apps under JES2.
Tried starting up a SYSVIEW task under JES2 but received the following errors:

S SYSVUSER,SUB=JES2
$HASP100 SYSVUSER ON STCINRDR $ACFJ227 ACF2/JES2 CONTROL BLOCK ERROR, SUBSYSTEM DIRECTORY ENTRY NOT FOUND

Tried logging on to TSO using a subsys parameter but it failed, possibly due to ACF2. 
Can jobs be started under JES2 and still get ACF2 functionality or is ACF2 not functional in a mixed JES3/JES2 environment?
 

Environment

z/OS 2.3
ACF2 16.0
JES2/ JES3

Cause

IEE252I MEMBER IEFSSN00 FOUND IN SYS1.PARMLIB
S JES3
ASA009I SYNTAX ERROR IN PARMLIB MEMBER=IEFSSN00 ON LINE 4, 413         (Error condition)
POSITION 17: WHEN START IS SPECIFIED,
THE FOLLOWING MUST ALSO BE SPECIFIED:
(PRIMARY(YES)).
DETECTING MODULE IS IEFJPACT. INPUT LINE:
PRIMARY(NO) START(NO)
IEFJ001I IEFSSN00 LINE 4: ERROR IN SUBSYSTEM DEFINITION, REFER TO
HARDCOPY LOG

Resolution

In this case, a correction was needed for IEFSSNxxx parm :
SUBSYS SUBNAME(JES2) PRIMARY(NO) START(NO)

Remove START(NO) from the SUBSYS statement for JES2 :
SUBSYS SUBNAME(JES2) PRIMARY(NO)

Note:
The above change may not be the 'only' reason for a $ACFJ227 error. This, however, points to a JES condition.
Review all relevant diagnostic documents before reaching a conclusion.