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Linkage conventions z/OS MVS Programming: Extended Addressability Guide SA23-1394-00 |
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In z/OS® R2, program entry is in AMODE 24 or AMODE 31; therefore linkage conventions you have used in S/390® apply, which means passing 4-byte parameter lists and a 72-byte save area. An older program changing from AMODE 31 to AMODE 64 to exploit z/Architecture® instructions should expect to receive 31-bit addresses and the 72-byte save area from its callers. If you are running in AMODE 64 and want to use an address a caller has passed to you, the high-order half of the GPR will probably not be cleared to zeros. As soon as you receive this address, use the Load Logical G Thirty One Bits (LLGT or LLGTR) instruction to change this 31-bit address into a 64-bit address that you can use. |
Copyright IBM Corporation 1990, 2014
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