Updating the table from previous post (Thread Count supported by JVM on various OSs  ) for Java 1.6
OS(32-bit)  |    Java-Version  |    Heap-Size  |    ThreadStackSize  |    Thread-count  |   
RHEL  |    1.5  |    1024m  |    Default  |    3636  |   
RHEL  |    1.5  |    1250m  |    Default  |    3196  |   
RHEL  |    1.5  |    1536m  |    Default  |    2632  |   
RHEL  |    1.5  |    1750m  |    Default  |    2206  |   
RHEL  |    1.5  |    2g  |    Default  |    1615  |   
RHEL  |    1.5  |    1024m  |    128k  |    13947  |   
RHEL  |    1.5  |    1250m  |    128k  |    12245  |   
RHEL  |    1.5  |    1536m  |    128k  |    10083  |   
RHEL  |    1.5  |    1750m  |    128k  |    8466  |   
RHEL  |    1.5  |    2g  |    128k  |    6215  |   
RHEL  |    1.5  |    1024m  |    256k  |    7183  |   
RHEL  |    1.5  |    1250m  |    256k  |    6301  |   
RHEL  |    1.5  |    1536m  |    256k  |    5190  |   
RHEL  |    1.5  |    1750m  |    256k  |    4365  |   
RHEL  |    1.5  |    2g  |    256k  |    3198  |   
WinXP  |    1.5  |    1024m  |    Default  |    3388  |   
WinXP  |    1.5  |    1250m  |    Default  |    2495  |   
WinXP  |    1.5  |    1536m  |    Default  |    NA  |   
WinXP  |    1.5  |    1750m  |    Default  |    NA  |   
WinXP  |    1.5  |    2g  |    Default  |    NA  |   
WinXP  |    1.5  |    1024m  |    128k  |    3388  |   
WinXP  |    1.5  |    1250m  |    128k  |    2495  |   
WinXP  |    1.5  |    1536m  |    128k  |    NA  |   
WinXP  |    1.5  |    1750m  |    128k  |    NA  |   
WinXP  |    1.5  |    2g  |    128k  |    NA  |   
WinXP  |    1.5  |    1024m  |    256k  |    855  |   
WinXP  |    1.5  |    1250m  |    256k  |    631  |   
WinXP  |    1.5  |    1536m  |    256k  |    NA  |   
WinXP  |    1.5  |    1750m  |    256k  |    NA  |   
WinXP  |    1.5  |    2g  |    256k  |    NA  |   
RHEL  |    1.6  |    1024m  |    Default  |    5851  |   
RHEL  |    1.6  |    1250m  |    Default  |    5156  |   
RHEL  |    1.6  |    1536m  |    Default  |    4272  |   
RHEL  |    1.6  |    1750m  |    Default  |    3603  |   
RHEL  |    1.6  |    2g  |    Default  |    2689  |   
RHEL  |    1.6  |    1024m  |    128k  |    14005  |   
RHEL  |    1.6  |    1250m  |    128k  |    12323  |   
RHEL  |    1.6  |    1536m  |    128k  |    10213  |   
RHEL  |    1.6  |    1750m  |    128k  |    8640  |   
RHEL  |    1.6  |    2g  |    128k  |    6422  |   
RHEL  |    1.6  |    1024m  |    256k  |    7278  |   
RHEL  |    1.6  |    1250m  |    256k  |    6406  |   
RHEL  |    1.6  |    1536m  |    256k  |    5308  |   
RHEL  |    1.6  |    1750m  |    256k  |    4486  |   
RHEL  |    1.6  |    2g  |    256k  |    3340  |   
WinXP  |    1.6  |    1024m  |    Default  |    2657  |   
WinXP  |    1.6  |    1250m  |    Default  |    1991  |   
WinXP  |    1.6  |    1536m  |    Default  |    NA  |   
WinXP  |    1.6  |    1750m  |    Default  |    NA  |   
WinXP  |    1.6  |    2g  |    Default  |    NA  |   
WinXP  |    1.6  |    1024m  |    128k  |    6285  |   
WinXP  |    1.6  |    1250m  |    128k  |    4774  |   
WinXP  |    1.6  |    1536m  |    128k  |    NA  |   
WinXP  |    1.6  |    1750m  |    128k  |    NA  |   
WinXP  |    1.6  |    2g  |    128k  |    NA  |   
WinXP  |    1.6  |    1024m  |    256k  |    3312  |   
WinXP  |    1.6  |    1250m  |    256k  |    2478  |   
WinXP  |    1.6  |    1536m  |    256k  |    NA  |   
WinXP  |    1.6  |    1750m  |    256k  |    NA  |   
WinXP  |    1.6  |    2g  |    256k  |    NA  |   
Cheers,
Sarang