You might have thought I could use the -d switch to gnatbind:
-dnn[k|m] Default primary stack size = nn [kilo|mega] bytes -Dnn[k|m] Default secondary stack size = nn [kilo|mega] bytes
Unfortunately, this seemed to have no effect.
The Mac ld has the switch -stack_size:
-stack_size size Specifies the maximum stack size for the main thread in a program. Without this option a program has a 8MB stack. The argument size is a hexadecimal number with an optional lead- ing 0x. The size should be an even multiple of 4KB, that is the last three hexadecimal digits should be zero.
so to allocate a 16 Mb stack, use
gnatmake foo.adb -largs -Wl,-stack_size,0x1000000