This is part of Win16 API which allow to create versions of program from one source code to run under OS/2 and Win16. Under OS/2 program can be running under Win-OS/2 if program is Windows NE executable, and with help on Windows Libraries for OS/2, if it is OS/2 NE executable. Here is a WLO to OS/2 API mapping draft
Returns the current size (in bytes) of a local memory object.
UINT WINAPI LocalSize( HLOCAL hMem );
hMem – Handle to the memory object.
Returns the size of the block, or zero if the handle is invalid or the object has been discarded.
Call GetLastError for extended error information.
The returned size may be larger than the originally requested size because of internal alignment.
Use LocalFlags first to check whether the block has been discarded.
UINT size = LocalSize(hMem);
push hMem call LocalSize