Linkage to each function is through the default linkage provided by the METAL option of the C compiler. This assumes that GPR 13 points to a stack frame in a contiguous stack, and that the forward pointer in the stack frame contains the address of the next available byte in the stack. The stack frame requirements for each function are documented in Function stack requirements so that the caller knows how much space to reserve.
The library functions support AMODE 31 and AMODE 64.
The library functions (with the exception of a few AR mode supporting functions) expect the ASC mode to be Primary on entry. The AR mode support part of Metal C ensures that this is enforced; however, if calling these library functions from within HLASM embedded statements or their own HLASM programs, you need to manage ASC mode to meet this requirement.
The library functions support IEEE floating point numbers.
The library uses code page IBM-1047 and the En_US locale definitions to perform its functions.