The program static data area in IEBCOPY is at the start of the
load module and is page aligned. It is the CSECT IEBCOMCA and is always
based on R4. Certain control blocks always appear at a fixed offset.
Most useful are:
- MCA+X'1000' Input file D$C
- MCA+X'1200' Output file D$C
- MCA+X'1400' SYSUT3 D$C
- MCA+X'1600' SYSUT4 D$C
- MCA+X'1800' Load file D$C
- MCA+X'1A00' Unload file D$C
The D$C contains a DD name and a DCB pointer at offset +X'60',
the DEVTAB at +X'A0', the JFCB at +X'C0' and the DSCB
at +X'174'.