Problem with Cargo - Trying to use link-args - stack

Question

At the moment I'm trying to link my Rust library with my Java project with JNI.
When I build my Rust library with cargo build there are no errors. My code works!
My problem is the interface between Java and Rust. When I run my Java project with InteliJ there appears this error message:
OpenJDK 64-Bit Server VM warning: You have loaded library /home/.../Encoding/libs/poc which might have disabled stack guard. The VM will try to fix the stack guard now.
It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'.
Exception in thread "main" java.lang.UnsatisfiedLinkError: cannot read file data: Is a directory
at java.base/java.lang.ClassLoader$NativeLibrary.load0(Native Method)
at java.base/java.lang.ClassLoader$NativeLibrary.load(ClassLoader.java:2445)
at java.base/java.lang.ClassLoader$NativeLibrary.loadLibrary(ClassLoader.java:2501)
at java.base/java.lang.ClassLoader.loadLibrary0(ClassLoader.java:2700)
at java.base/java.lang.ClassLoader.loadLibrary(ClassLoader.java:2630)
at java.base/java.lang.Runtime.load0(Runtime.java:768)
at java.base/java.lang.System.load(System.java:1837)
at com.example.Main.<clinit>(Main.java:16)
My next step was to compile my Rust library with execstack with the following command:
cargo build --verbose -Z build-std=core,alloc -c link-args=-znoexecstack
Another method for me was to add this arguments to my Cargo.toml:
[lib]
link-args = ["-z", "noexecstack"]
When I try to build my Rust library now, these arguments will be ignored:
$ cargo build
warning: unused manifest key: lib.link-args
Compiling poc v0.1.0 (/home/.../Encoding/libs/poc)
Finished dev [unoptimized + debuginfo] target(s) in 1.50s
Now I hope that anyone of you can help me with my problem. I would be very thankful!
Maybe this is also interesting: my project structure
Encoding
|-- libs
|-- poc
|-- src
|-- lib.rs
|-- cargo.toml
|-- src
|-- main/java/org/example
|-- Main.java
|--target
|-- ...
|-- pom.xml
As described I tried following commands
cargo build --verbose -Z build-std=core,alloc -c link-args=-znoexecstack
cargo build with [lib] -> link-args = ["-z", "noexecstack"]
And I need this to run my Java project without the risk of an executable stack!