Call external program in background mode

Hi,

I am creating a PO using bapi BAPI_PO_CREATE1 in exit USEREXIT_SAVE_DOCUMENT_PREPARE.

I dont want to write the code in my exit. Instead I want to write the code in a Z program and call it in my exit.

My Problem.

How do I call my z program in my exit so that I can pass internal tables from my exit to the z program. Also I want to schedule the call of my external program for background processing.

I am trying with SUBMIT ZPROG AND RETURN. But not able to pass an internal table.

I tried PERFORM BAPI_PO_CREATE IN PRGRAM ZPROG, but in this case not able to schedule it in background.

Please advise.

Regards,

Shobhit