HP MLIB User's Guide Vol. 2 7th Ed.

1088 HP MLIB User’s Guide
General interlanguage programming rules
However, if the struct is allocated using malloc(), it will be 8-byte aligned. So if
a program allocates the complex8_t struct with malloc(), and then passes it
using pointers, then the data will be 8-byte aligned. For example:
complex8_t*zarray=malloc(n*sizeof(complex8_t))
will be 8-byte aligned.
One way to ensure that static storage is aligned is to use the C compiler’s align
#pragma to enforce 8-byte alignment. For example:
#pragma align 8
static complex8_t alpha={1,0,2,0};
forces 8-byte alignment for alpha.