Since no one have helped you I will give this information.
The POPs manual is the king of manuals when dealing with assembler.
POP is the Principle of Operations.
The actual instructions are as follows and should be built into a startup macro.
This the from my days in the 370 market place.
an online version can be found here. http://publibz.boulder.ibm.com/cgi-bin/ ... 0504121320
Assembler codeing can begin in any collum other then 1. if its in col. 1 then its a label.
The called pgm must have the follwing instructions to follow the rules.
stm r14,r12,12(r13) save the callers registers into the new pgms save area. ( of couse this is non-reentrant)
balr r12,0 set addresserrablilty with r12 for use as base reg
using *,r12 give address ability to the next 4096 bytes with addressability
st r13,savearea+4 save the old savearea 4 into the new save area
la r13,savearea load r13 with new savearea address
st r13,savearea+8 save new savearea address
your special code
to return to caller
l r13,4(r13) restore the callers save area
lm r14,r12,12(r13) restore the original registers from who called you
br r14 return to caller
savearea 0d allign on double word boundary.
Have at it. Any questions. TKS