For IBM JDK 6 and 7 parameter -server is not added for PC and HC, server-one and server-two processes contain -server parameter.
On OracleJDK and OpenJDK it's added by default for domain.sh, in standalone.sh for IBM JDK parameter -server is added.

Problem is in domain.sh script, part starting with line 76.

IBM JDK 6 version output:
java version "1.6.0"
Java(TM) SE Runtime Environment (build pxi3260sr10fp1-20120321_01(SR10 FP1))
IBM J9 VM (build 2.4, JRE 1.6.0 IBM J9 2.4 Linux x86-32 jvmxi3260sr10fp1-20120202_101568 (JIT enabled, AOT enabled)
J9VM - 20120202_101568
JIT - r9_20111107_21307ifx1
GC - 20120202_AA)
JCL - 20120320_01

IBM JDK 7 version output:
java version "1.7.0"
Java(TM) SE Runtime Environment (build pxi3270-20110827_01)
IBM J9 VM (build 2.6, JRE 1.7.0 Linux x86-32 20110810_88604 (JIT enabled, AOT enabled)
J9VM - R26_Java726_GA_20110810_1208_B88592
JIT - r11_20110810_20466
GC - R26_Java726_GA_20110810_1208_B88592
J9CL - 20110810_88604)
JCL - 20110809_01 based on Oracle 7b147