composer runs out of memory

[Cary Lewis]

I am running cygwin 64 bit and have installed the latest 7.3.7 version of
php.

When I attempt to run composer, I get a fatal out of memory error.

In my php.ini file I have set max memory to -1, and

php -r "echo ini_get('memory_limit').PHP_EOL;"
-1

confirms it.

I saw a stackoverflow article related to this issue, but the resolution was
to use the 64bit version of cygwin and 64bit of php, which I appear to have:

file $(which php)
/usr/bin/php: PE32+ executable (console) x86-64, for MS Windows

Can someone please provide an explanation and work around for this?